allow system_server oemfs read access

Bug: 17954291
Change-Id: Ia904fff65df5142732928561d81ea0ece0c52a8d
diff --git a/system_server.te b/system_server.te
index e55a435..97d159d 100644
--- a/system_server.te
+++ b/system_server.te
@@ -391,7 +391,7 @@
 allow system_server cgroup:dir { remove_name rmdir };
 
 # /oem access
-allow system_server oemfs:dir search;
+r_dir_file(system_server, oemfs)
 
 ###
 ### Neverallow rules