Set device-specific overlays correctly

Change-Id: I64cfedbe7da797658472fcca6dac761b993333dd
Revert fstab.g2

fstab.g2 for lgl22 moved to device-specific tree:
https://github.com/kbc-developers/android_device_lge_lgl22/blob/d610b8bba3236a777e793ecb860f9a1332f60566/rootdir/fstab.g2

Change-Id: I6c9916c72b859b37f15d9e54b1730c892fb80edb