Hi Sir,
I suggest you try to compile the kernel with eMMC driver enabled:
1) if you faced such error with dmesg:
error:mmc0:unrecongnised EXT_CSD revision 7
mmc0:error -22 whilst initialising MMC card
try to apply a patch here:
kernel/driver/mmc/core/mmc.c
patch :
-if (card->ext_csd.rev > 6)
+if (card->ext_csd.rev > 7)
2 ) enable eMMC driver:
After you applied the new kernel, it should detect the eMMC flash disk with "fdisk -l " command. Then you can try to dd the whole system into eMMC flash and boot the system from internal eMMC flash. No need usb drive any more.