ext4: enable journal checksum when metadata checksum feature enabled

If metadata checksumming is turned on for the FS, we need to tell the
journal to use checksumming too.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org