xfs: Remove the macro XFS_BUF_ERROR and family

Remove the definitions and usage of the macros XFS_BUF_ERROR,
XFS_BUF_GETERROR and XFS_BUF_ISERROR.

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_attr.c b/fs/xfs/xfs_attr.c
index cbae424..160bcdc 100644
--- a/fs/xfs/xfs_attr.c
+++ b/fs/xfs/xfs_attr.c
@@ -2121,8 +2121,7 @@
 
 		bp = xfs_buf_get(mp->m_ddev_targp, dblkno, blkcnt,
 				 XBF_LOCK | XBF_DONT_BLOCK);
-		ASSERT(bp);
-		ASSERT(!XFS_BUF_GETERROR(bp));
+		ASSERT(!xfs_buf_geterror(bp));
 
 		tmp = (valuelen < XFS_BUF_SIZE(bp)) ? valuelen :
 							XFS_BUF_SIZE(bp);