xfs/53[238]: Disable realtime inherit flag

xfs/53[238]: Disable realtime inherit flag

The minimum length space allocator (i.e.
xfs_bmap_exact_minlen_extent_alloc()) depends on the underlying
filesystem to be fragmented so that there are enough one block sized
extents available to satify space allocation requests.

xfs/{532,533,538} tests issue space allocation requests for metadata
(e.g. for blocks holding directory and xattr information). With
realtime filesystem instances, these tests would end up fragmenting
the space on realtime device. Hence minimum length space allocator
fails since the regular filesystem space is not fragmented and hence
there are no one block sized extents available.

Thus, this commit disables realtime inherit flag (if any) on root
directory so that space on data device gets fragmented rather than
realtime device.

Suggested-by: Darrick J. Wong <djwong@kernel.org>
Reported-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>