xfs: strengthen rtalloc query range checks

xfs: strengthen rtalloc query range checks

Source kernel commit: 8ad560d2565e64b8be0cf5901c1e8fe034ac5599

Strengthen the rtalloc range query checks to make sure that the keys do
not run off the end of the realtime device inappropriately.  Note that
the query range functions require units of rt extents, not blocks,
despite the type name.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Bill O'Donnell <billodo@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>