xfs: support XFS_BMAPI_REMAP in xfs_bmap_del_extent_delay

xfs: support XFS_BMAPI_REMAP in xfs_bmap_del_extent_delay

Source kernel commit: f42c652434de5e26e02798bf6a0c2a4a8627196b

The zone allocator wants to be able to remove a delalloc mapping in the
COW fork while keeping the block reservation.  To support that pass the
flags argument down to xfs_bmap_del_extent_delay and support the
XFS_BMAPI_REMAP flag to keep the reservation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>