Allow DRM hal to access fd allocated by mediaserver

Test: gts-tradefed run gts -m GtsMediaTestCases -t com.google.android.media.gts.MediaPlayerTest#testLLAMA_H264_BASELINE_240P_800_DOWNLOADED_V0_SYNC

bug:37548390
Change-Id: I9c2d446118d3a5f729730b75ec117954e383159b

public/hal_drm.te

@@ -27,6 +27,9 @@ allow hal_drm cgroup:file w_file_perms;
 allow hal_drm ion_device:chr_file rw_file_perms;
 allow hal_drm hal_graphics_allocator:fd use;
 
+# Allow access to fds allocated by mediaserver
+allow hal_drm mediaserver:fd use;
+
 # Allow access to app_data and media_data_files
 allow hal_drm media_data_file:dir create_dir_perms;
 allow hal_drm media_data_file:file create_file_perms;