private: hal_widevine_system: support private storage

- mediadrm_system_data_file file type
- make  it private to hal_widevine_system

Bug: 371777025
Test: lunch qemu_trusty_arm64-trunk_staging-userdebug
Change-Id: I5bd28eb4f2eaa44bb0b5a934b7919d2b959ec098
diff --git a/private/file.te b/private/file.te
index 6bdcc39..6de346a 100644
--- a/private/file.te
+++ b/private/file.te
@@ -14,6 +14,9 @@
 type fs_bpf_uprobestats, fs_type, bpffs_type;
 type fs_bpf_memevents, fs_type, bpffs_type;
 
+# /data/system/mediadrm
+type mediadrm_system_data_file, file_type, data_file_type, core_data_file_type;
+
 # /data/misc/storaged
 type storaged_data_file, file_type, data_file_type, core_data_file_type;