integros

I'm sorry, my bad, I accidentally include UHS-I SD card patch on that test kernel, the DTB to be exact, and apparently your card does not compatible. You can read more about this at SDIO (SD Card) page on our wiki. You just need to install the linux-image package. No need to install the dtb and headers.
 
Regarding XOR, yes i notice it too. I think it would default to software implementation first then override later by async_tx if the hardware offload engine is available.
You can see on kernel message below, the async_tx initialized quite late compared to xor and raid6.
[ 0.004600] xor: measuring software checksum speed [ 0.043885] arm4regs : 2533.000 MB/sec [ 0.083885] 8regs : 1947.000 MB/sec [ 0.123884] 32regs : 1804.000 MB/sec [ 0.163884] neon : 1840.000 MB/sec [ 0.163887] xor: using function: arm4regs (2533.000 MB/sec) <...> [ 0.240055] raid6: int32x1 gen() 262 MB/s [ 0.307944] raid6: int32x1 xor() 271 MB/s [ 0.376037] raid6: int32x2 gen() 351 MB/s [ 0.443939] raid6: int32x2 xor() 329 MB/s [ 0.512026] raid6: int32x4 gen() 393 MB/s [ 0.579947] raid6: int32x4 xor() 319 MB/s [ 0.647890] raid6: int32x8 gen() 422 MB/s [ 0.715956] raid6: int32x8 xor() 324 MB/s [ 0.783897] raid6: neonx1 gen() 1212 MB/s [ 0.851888] raid6: neonx1 xor() 1150 MB/s [ 0.919918] raid6: neonx2 gen() 1296 MB/s [ 0.987897] raid6: neonx2 xor() 1347 MB/s [ 1.055893] raid6: neonx4 gen() 1349 MB/s [ 1.123902] raid6: neonx4 xor() 1377 MB/s [ 1.191883] raid6: neonx8 gen() 1073 MB/s [ 1.259882] raid6: neonx8 xor() 1041 MB/s [ 1.259885] raid6: using algorithm neonx4 gen() 1349 MB/s [ 1.259888] raid6: .... xor() 1377 MB/s, rmw enabled [ 1.259891] raid6: using neon recovery algorithm <...> [ 1.425544] mv_xor f1060800.xor: Marvell shared XOR driver [ 1.457595] mv_xor f1060800.xor: Marvell XOR (Descriptor Mode): ( xor cpy intr ) [ 1.457693] mv_xor f1060900.xor: Marvell shared XOR driver [ 1.485586] mv_xor f1060900.xor: Marvell XOR (Descriptor Mode): ( xor cpy intr ) <...> [ 4.580251] async_tx: api initialized (async)  
I built another test kernel with "DMA Engine verbose debugging" option enabled. These lines printed repeatedly (well, not exactly same address) during dd from /dev/zero to /dev/md0 and the interrupt counter increased.
[ 416.505470] mv_xor f1060800.xor: mv_xor_prep_dma_xor src_cnt: 1 len: 4096 dest 0x216eb000 flags: 32 [ 416.514571] mv_xor f1060800.xor: mv_xor_prep_dma_xor sw_desc ed89d780 async_tx ed89d79c [ 416.522719] mv_xor f1060800.xor: mv_xor_tx_submit sw_desc ed89d780: async_tx ed89d79c [ 416.530582] mv_xor f1060800.xor: mv_chan_start_new_chain 190: sw_desc ed89d780 [ 416.537865] mv_xor f1060800.xor: activate chan. [ 416.542544] mv_xor f1060800.xor: intr cause 2 [ 416.546915] mv_xor f1060800.xor: mv_chan_clear_eoc_cause, val 0xfffffff8 [ 416.553658] mv_xor f1060800.xor: mv_chan_slot_cleanup 280 [ 416.559076] mv_xor f1060800.xor: current_desc 7f056380 [ 416.564253] mv_xor f1060800.xor: mv_chan_clean_completed_slots 227 [ 416.570461] mv_xor f1060800.xor: mv_desc_clean_slot 247: desc ed89d780 flags 32 [ 416.577803] mv_xor f1060800.xor: mv_xor_prep_dma_xor src_cnt: 1 len: 4096 dest 0x2ceaf000 flags: 32 [ 416.586894] mv_xor f1060800.xor: mv_xor_prep_dma_xor sw_desc ed89da00 async_tx ed89da1c [ 416.595019] mv_xor f1060800.xor: mv_xor_tx_submit sw_desc ed89da00: async_tx ed89da1c [ 416.602890] mv_xor f1060800.xor: mv_chan_start_new_chain 190: sw_desc ed89da00 [ 416.610142] mv_xor f1060800.xor: activate chan.  
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Initially I had no idea why the update break the system. I did several time testing the update scenario from 5.64 to 5.68 & 5.69 (both are internal release). Then I realized that I missed that you started from 5.67 which i thought never released. 
 
I would say,  the 5.67 contains broken u-boot 2018.11. It only compatible with boot-mvebu-next.cmd. It already fixed on this commit part of PR #1169.  So version 5.68 onward should be compatible with both, boot-marvell.cmd and boot-mvebu-next.cmd.
 
Since the fix just modify the environment variable, I suggest to run these commands to make it also compatible with boot-marvell.cmd. 
setenv boot_a_script 'load ${devtype} ${devnum}:${distro_bootpart} ${scriptaddr} ${prefix}${script}; setenv boot_interface ${devtype};source ${scriptaddr}' setenv loadaddr 0x02000000 setenv fdt_addr ${fdt_addr_r} saveenv I have tested it on 5.67

Fixed by removing broken files from repository:
pool/main/l/linux-bionic-root-next-helios4/linux-bionic-root-next-helios4_5.70_armhf.deb
pool/main/l/linux-stretch-root-next-helios4/linux-stretch-root-next-helios4_5.70_armhf.deb