xfs: ensure that fpunch, fcollapse, and finsert operations are aligned to rt extent size

Make sure that any fallocate operation that requires the range to be
block-aligned also checks that the range is aligned to the realtime
extent size.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>