app: aboot: Check device's status in cmd_flash_meta_img before flashing

It is risky that the device will bypass the critical partition when
device is locked. Because the image maybe a package of all partitions.
So forbid to flash image when device is locked.

CRs-Fixed: 982266
Change-Id: I0fff412419702e11bd4098e572be37e9dac20cf0
1 file changed