xfs: Remove the macro XFS_BUF_PTR

Remove the definition and usages of the macro XFS_BUF_PTR.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
diff --git a/fs/xfs/xfs_rtalloc.h b/fs/xfs/xfs_rtalloc.h
index 09e1f4f..f7f3a35 100644
--- a/fs/xfs/xfs_rtalloc.h
+++ b/fs/xfs/xfs_rtalloc.h
@@ -47,7 +47,7 @@
 #define	XFS_SUMOFFSTOBLOCK(mp,s)	\
 	(((s) * (uint)sizeof(xfs_suminfo_t)) >> (mp)->m_sb.sb_blocklog)
 #define	XFS_SUMPTR(mp,bp,so)	\
-	((xfs_suminfo_t *)((char *)XFS_BUF_PTR(bp) + \
+	((xfs_suminfo_t *)((bp)->b_addr + \
 		(((so) * (uint)sizeof(xfs_suminfo_t)) & XFS_BLOCKMASK(mp))))
 
 #define	XFS_BITTOBLOCK(mp,bi)	((bi) >> (mp)->m_blkbit_log)