m7-common: Add platform-specific SELinux policy

Change-Id: I25699e215ceb78ef90cdd7bfefaf7d123b6fcad4
Revert "Revert "Revert "m7-common: use permissive SELinux"""

* Run in enforcing mode

This reverts commit 86322cf314651e46457846f725d7b2007ddbe17b.

Change-Id: I07b62823f1667e8bf1a3bff9ee9a2c2bdb02a22e