xfs: add missing assert in xfs_fsmap_owner_from_rmap

The fsmap handler shouldn't fail silently if the rmap code ever feeds it
a special owner number that isn't known to the fsmap handler.

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