Short circuit system and root uids in appop checks

When switching to using the permission state for the appop value we'll
have the problem that system and root don't have permission state in the
unified permission system so the result will be a rejection. We can
simply avoid making the check for UIDs that are always supposed to
permit.

Test: Boot
Bug: 266164193
Fixes: 333938416
Change-Id: I39d5125cc7b59970b2c7cc8bfbc71f89bdee5771