audit mtp sync permission

Determine if the following rule can be removed:

allow kernel untrusted_app:fd use

Bug: 25331459
Change-Id: I4ef9f376d7fc1d2bdfba69b2fb3e24d49ac136ad

kernel.te

@@ -43,6 +43,9 @@ allow kernel self:security setcheckreqprot;
 # MTP sync (b/15835289)
 # kernel thread "loop0", used by the loop block device, for ASECs (b/17158723)
 allow kernel { priv_app untrusted_app }:fd use;
+# privileged apps have moved to the priv_app domain. Determine
+# if this permission is still needed. b/25331459
+auditallow kernel untrusted_app:fd use;
 allow kernel sdcard_type:file { read write };
 
 # Allow the kernel to read OBB files from app directories. (b/17428116)