otasigcheck: Use an explicit exit code for failures

Change-Id: I2b5860ea427a4db7e29b55cc632b92c6e2910494
sepolicy: Fix permissions for service.adb.tcp.port

This makes the rule more specific by overriding the upstream sepolicy.
Also adds the adbd context which is necessary for "adb tcpip".

Change-Id: Ia17eb56fc1682ab248764329e88eebd2a4075c97