xfs: fix for variable set but not used warning

Fix below kernel warning:

fs/xfs/scrub/repair.c:539:19: warning: variable 'agno' set but not used [-Wunused-but-set-variable]
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: Nsunliming <sunliming@kylinos.cn>
Reviewed-by: NDarrick J. Wong <djwong@kernel.org>
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>

fs/xfs/scrub/repair.c

@@ -536,14 +536,12 @@ xrep_reap_block(
 {
 	struct xfs_btree_cur		*cur;
 	struct xfs_buf			*agf_bp = NULL;
-	xfs_agnumber_t			agno;
 	xfs_agblock_t			agbno;
 	bool				has_other_rmap;
 	int				error;
 
-	agno = XFS_FSB_TO_AGNO(sc->mp, fsbno);
 	agbno = XFS_FSB_TO_AGBNO(sc->mp, fsbno);
-	ASSERT(agno == sc->sa.pag->pag_agno);
+	ASSERT(XFS_FSB_TO_AGNO(sc->mp, fsbno) == sc->sa.pag->pag_agno);
 
 	/*
 	 * If we are repairing per-inode metadata, we need to read in the AGF