Add keystore add_auth

This is for the new addAuthToken keystore method from
I7f7647d9a36ea453ec6d62fc84087ca8f76e53dd. These tokens will be used to
authorize keymaster operations. The tokens are HMAC'd and so shouldn't
be fakeable but this is still limited to system_server only.

Change-Id: I3ff46b676ecac8a878d3aa0a25ba9a8b0c5e1f47

access_vectors

@@ -909,6 +909,7 @@ class keystore_key
 	reset_uid
 	sync_uid
 	password_uid
+	add_auth
 }
 
 class debuggerd

system_server.te

@@ -455,6 +455,7 @@ allow system_server keystore:keystore_key {
 	reset_uid
 	sync_uid
 	password_uid
+	add_auth
 };
 
 # Allow system server to search and write to the persistent factory reset