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_da_btree.c b/fs/xfs/xfs_da_btree.c
index 2925726..5d9290d 100644
--- a/fs/xfs/xfs_da_btree.c
+++ b/fs/xfs/xfs_da_btree.c
@@ -2040,7 +2040,7 @@
 		case 0:
 			bp = xfs_trans_get_buf(trans, mp->m_ddev_targp,
 				mappedbno, nmapped, 0);
-			error = bp ? XFS_BUF_GETERROR(bp) : XFS_ERROR(EIO);
+			error = bp ? bp->b_error : XFS_ERROR(EIO);
 			break;
 		case 1:
 		case 2: