m8: use device-specific sepolicies

Change-Id: Ia46b46e9b0fb7968144b2a6fa852f256cfaea3a4
[TEMP] m8: disable overlays that don't exist yet

Change-Id: I604c4b7c39b07acf62d6e44b785c9a65f6cb56b8
[TEMP] m8: don't build dotcase yet

Change-Id: Icf3c98882ab76e160d262f6c40867c88c1bf18d1
Update proprietary vendor path