System cannot run into bootloader/recovery mode once there is unknown cmd
in misc partition as:
1. uboot will never clean the unknown cmd.
2. init will never overwrite the unknown cmd.

arm2_8q:/ # reboot bootloader
init: [libfs_mgr]fs_mgr_read_fstab_dt(): failed to read fstab from dt
init: reboot-bootloader: Error writing bootloader_message: Bootloader command pending.
init: Reboot start, reason: reboot,bootloader, rebootTarget: bootloader

Change-Id: I51043e7cbde3f3e508c5fe99e9dba27e5f99f443
Signed-off-by: guoyin.chen <guoyin.chen@nxp.com>