Transcoding: Enable Transcoding service binder call to app.

This is needed for the transcoding service to callback to the
client through ITranscodingClientCallback interface.

Bug: 145628554
Test: atest MediaTranscodeManagerTest
Change-Id: I239259ed702fa01c235f57e0a96e887472365834
diff --git a/public/mediatranscoding.te b/public/mediatranscoding.te
index 5b64083..85c4a6c 100644
--- a/public/mediatranscoding.te
+++ b/public/mediatranscoding.te
@@ -10,6 +10,7 @@
 
 allow mediatranscoding system_server:fd use;
 allow mediatranscoding activity_service:service_manager find;
+allow mediatranscoding untrusted_app:binder call;
 
 # mediatranscoding should never execute any executable without a
 # domain transition