mediacodec: grant access to surfaceflinger

avc:  denied  { find } for service=SurfaceFlinger scontext=u:r:mediacodec:s0
tcontext=u:object_r:surfaceflinger_service:s0 tclass=service_manager

Bug: 26990688
Change-Id: Ie7c5f6d879c286375eb52ef4c6b84726aa4f1ba2

mediacodec.te

@@ -12,6 +12,7 @@ binder_call(mediacodec, appdomain)
 binder_service(mediacodec)
 
 allow mediacodec mediacodec_service:service_manager add;
+allow mediacodec surfaceflinger_service:service_manager find;
 allow mediacodec gpu_device:chr_file rw_file_perms;
 allow mediacodec video_device:chr_file rw_file_perms;
 allow mediacodec video_device:dir search;