Do not include common SE policies automatically

Automatic additions to BOARD_SEPOLICY_UNION from Android.mk do not
guarantee order or precedence of rules. More often than not, these
rules get included _after_ the device's own, which makes
it impossible for the device to extend them, or even to use types
defined here.

Manually include these in the device's BoardConfig with
$(call inherit-product, device/qcom/sepolicy/sepolicy.mk) before
its own specific BOARD_SEPOLICY_DIRS (if any) instead. Or just
include files piecemeal.

Change-Id: I2ce0c3ec325906a46570b26c5f0c2018390d2ec9