MA-11259 [Android] Fastboot oem unlock fail on imx8

MA-11259 [Android] Fastboot oem unlock fail on imx8

Commit 5dc5928 (MA-11108 [Android] decrypt lock store fail on imx7d) fix
some micros can't be enabled in drivers/usb/gadget/fastboot_lock_unlock.c
even if they have been defined in header files, which enables micro
CONFIG_ANDROID_AB_SUPPORT too. No "prdata" partition exist in Android or
Android Things which causes errors when try to read lock ability flag
from "prdata".

Moreover, imx8 don't use CAAM to decrypt/encrypt lock status, so we
should always return "FASTBOOT_UL_ENABLE" like what we have done on Android
Things.

Change-Id: Iff36485742815d5758e523ee2e6e6e1b4b8f7ac5
Signed-off-by: Luo Ji <ji.luo@nxp.com>