xfs: clean up xlog_align

Add suggested cleanups to commit 29db3370a1369541d58d692fbfb168b8a0bd7f41
from review that didn't end up being commited.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAlex Elder <aelder@sgi.com>

fs/xfs/xfs_log_recover.c

@@ -132,15 +132,10 @@ xlog_align(
 	int		nbblks,
 	xfs_buf_t	*bp)
 {
-	xfs_daddr_t	offset;
-	xfs_caddr_t	ptr;
+	xfs_daddr_t	offset = blk_no & ((xfs_daddr_t)log->l_sectBBsize - 1);
 
-	offset = blk_no & ((xfs_daddr_t) log->l_sectBBsize - 1);
-	ptr = XFS_BUF_PTR(bp) + BBTOB(offset);
-
-	ASSERT(ptr + BBTOB(nbblks) <= XFS_BUF_PTR(bp) + XFS_BUF_SIZE(bp));
-
-	return ptr;
+	ASSERT(BBTOB(offset + nbblks) <= XFS_BUF_SIZE(bp));
+	return XFS_BUF_PTR(bp) + BBTOB(offset);
 }