Is there a reason this is turned off? From linux-rockchip64-current.config:
#
# CD-ROM/DVD Filesystems
#
# CONFIG_ISO9660_FS is not set
# CONFIG_UDF_FS is not set
# end of CD-ROM/DVD Filesystems
Whereas most other configs have this enabled as modules. For example, in linux-sunxi64-current.config:
#
# CD-ROM/DVD Filesystems
#
CONFIG_ISO9660_FS=m
CONFIG_JOLIET=y
# CONFIG_ZISOFS is not set
CONFIG_UDF_FS=m
# end of CD-ROM/DVD Filesystems