Allow system_server to make keystore_data_file links

am: a67411c9

Change-Id: If2ab59c09b2ccf444281fdf9003e36119eb7295f

system_server.te

@@ -223,6 +223,7 @@ allow system_server system_data_file:dir create_dir_perms;
 allow system_server system_data_file:notdevfile_class_set create_file_perms;
 allow system_server keychain_data_file:dir create_dir_perms;
 allow system_server keychain_data_file:file create_file_perms;
+allow system_server keychain_data_file:lnk_file create_file_perms;
 
 # Manage /data/app.
 allow system_server apk_data_file:dir create_dir_perms;