UBIFS: fix a rare memory leak in ro to rw remounting path

When re-mounting from R/O mode to R/W mode and the LEB count in the superblock
is not up-to date, because for the underlying UBI volume became larger, we
re-write the superblock. We allocate RAM for these purposes, but never free it.
So this is a memory leak, although very rare one.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: stable@kernel.org
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 407c064..575ea83 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1585,6 +1585,7 @@
 		}
 		sup->leb_cnt = cpu_to_le32(c->leb_cnt);
 		err = ubifs_write_sb_node(c, sup);
+		kfree(sup);
 		if (err)
 			goto out;
 	}