mkfs: enable formatting with parent pointers

Enable parent pointer support in mkfs via the '-n parent' parameter.

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: move the no-V4 filesystem check to join the rest]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
7 files changed