xfs: xrep_reap_extents should not destroy the bitmap

Remove the xfs_bitmap_destroy call from the end of xrep_reap_extents
because this sort of violates our rule that the function initializing a
structure should destroy it.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>