I have updated the armbian-firmware to full package:
root@rock-3a:/lib/firmware/mediatek# ls -la /lib/firmware/mediatek/ | grep mt7915
-rw-rw-r-- 1 root root 3584 Feb 17 22:23 mt7915_eeprom.bin
-rw-rw-r-- 1 root root 3584 Feb 17 22:23 mt7915_eeprom_dbdc.bin
-rw-rw-r-- 1 root root 144544 Feb 17 22:23 mt7915_rom_patch.bin
-rw-rw-r-- 1 root root 116160 Feb 17 22:23 mt7915_wa.bin
-rw-rw-r-- 1 root root 1260960 Feb 17 22:23 mt7915_wm.bin
but my Mediatek 7915e seems to
https://www.armbian.com/participate/ (register to Jira, open a ticket similar to this one https://armbian.atlassian.net/browse/AR-1803
assign yourself to AR-1803 and the one you will be creating for MT7915E
solve both in one PR https://docs.armbian.com/Process_Contribute/ (specific instructions on what you need to do are in AR-1803)
Its a great and simple way to make a contribution to the open source project. Once merged, changes will be automatically pushed to beta.armbian.