UBIFS: fix a memory leak on error path.

In 'mount_ubifs()', in case of 'ubifs_leb_unmap()' falure,
free allocated resources.

Signed-off-by: Matthieu CASTET <matthieu.castet@parrot.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 010eea0..5fc5a09 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1320,7 +1320,7 @@
 			 */
 			err = ubifs_leb_unmap(c, c->gc_lnum);
 			if (err)
-				return err;
+				goto out_orphans;
 		}
 
 		err = dbg_check_lprops(c);