mm/hwpoison-inject.c: remove unnecessary null test before debugfs_remove_recursive

Fix checkpatch warning:
  "WARNING: debugfs_remove_recursive(NULL) is safe this check is probably not required"

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hwpoison-inject.c

@@ -72,8 +72,7 @@ DEFINE_SIMPLE_ATTRIBUTE(unpoison_fops, NULL, hwpoison_unpoison, "%lli\n");
 
 static void pfn_inject_exit(void)
 {
-	if (hwpoison_dir)
-		debugfs_remove_recursive(hwpoison_dir);
+	debugfs_remove_recursive(hwpoison_dir);
 }
 
 static int pfn_inject_init(void)