Split preloads into media_file and data_file

Untrusted apps should only access /data/preloads/media and demo directory.

Bug: 36197686
Test: Verified retail mode.
      Checked non-privileged APK cannot access /data/preloads
Change-Id: I8e9c21ff6aba799aa31bf06893cdf60dafc04446
diff --git a/private/platform_app.te b/private/platform_app.te
index 2817e5a..6b18d8f 100644
--- a/private/platform_app.te
+++ b/private/platform_app.te
@@ -56,5 +56,7 @@
 # Access to /data/preloads
 allow platform_app preloads_data_file:file r_file_perms;
 allow platform_app preloads_data_file:dir r_dir_perms;
+allow platform_app preloads_media_file:file r_file_perms;
+allow platform_app preloads_media_file:dir r_dir_perms;
 
 read_runtime_log_tags(platform_app)