xfs_mkfs: default to rtinherit=1 for zoned file systems

xfs_mkfs: default to rtinherit=1 for zoned file systems

Zone file systems are intended to use sequential write required zones
(or areas treated as such) for the main data store. And usually use the
data device only for metadata that requires random writes.

rtinherit=1 is the way to achieve that, so enabled it by default, but
still allow the user to override it if needed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[aalbersh remove accidental "inherit" word in commit desc.]