ubifs: Turn two ubifs_assert() into a WARN_ON()

We are going to pass struct ubifs_info to ubifs_assert()
but while unloading the UBIFS module we don't have the info
struct anymore.
Therefore replace the asserts by a regular WARN_ON().
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/ubifs/super.c

@@ -2306,8 +2306,8 @@ late_initcall(ubifs_init);
 
 static void __exit ubifs_exit(void)
 {
-	ubifs_assert(list_empty(&ubifs_infos));
-	ubifs_assert(atomic_long_read(&ubifs_clean_zn_cnt) == 0);
+	WARN_ON(list_empty(&ubifs_infos));
+	WARN_ON(atomic_long_read(&ubifs_clean_zn_cnt) == 0);
 
 	dbg_debugfs_exit();
 	ubifs_compressors_exit();