xfs: Fix a build warning in xfs_aops.c

Fix a build warning that slipped through.  Dave Chinner had posted
an updated version of his patch but the previous version--without
this fix--was what got committed.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Alex Elder <aelder@sgi.com>

fs/xfs/linux-2.6/xfs_aops.c

@@ -229,7 +229,7 @@ xfs_end_io(
 {
 	xfs_ioend_t	*ioend = container_of(work, xfs_ioend_t, io_work);
 	struct xfs_inode *ip = XFS_I(ioend->io_inode);
-	int		error;
+	int		error = 0;
 
 	/*
 	 * For unwritten extents we need to issue transactions to convert a