Do not trigger revoke-perm callbacks if no change

Revoking a permission might e.g. kill the the app. If a permission gets
revoked that was never granted there was no change, hence no need to call
the callbacks and also no need to kill the app.

Test: "pm clear" two times in a row. The second one did trigger a kill
before, not anymore.
Bug: 133830856
Change-Id: I357f2d939520ac78ef82ecf4feb7936455950fc4