sepolicy: allow writing firmware files in recovery mode.

FOTA upgrading requires writing firmware images into
vfat firmware partition in recovery mode.

Change-Id: I0bd61196ea7acf00582e58980aaeb3cf5128aa7a
diff --git a/common/recovery.te b/common/recovery.te
index c83bc97..210c405 100644
--- a/common/recovery.te
+++ b/common/recovery.te
@@ -3,7 +3,8 @@
     allow recovery sdcard_type:dir r_dir_perms;
     allow recovery sdcard_type:file r_file_perms;
     allow recovery vfat:dir r_dir_perms;
-    allow recovery vfat:file r_file_perms;
+    allow recovery vfat:file create_file_perms;
+    allow recovery vfat:file rw_file_perms;
     allow recovery system_data_file:file r_file_perms;
     allow recovery system_data_file:dir r_dir_perms;
     allow recovery RIDL_data_file:file r_file_perms;