xfs: small cleanup in xfs_lowbit64()

There are two checkpatch.pl complaints here because of the bad
indenting and because of the assignment inside the condition.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_bit.h

@@ -66,9 +66,12 @@ static inline int xfs_lowbit64(__uint64_t v)
 		n = ffs(w);
 	} else {	/* upper bits */
 		w = (__uint32_t)(v >> 32);
-		if (w && (n = ffs(w)))
+		if (w) {
+			n = ffs(w);
+			if (n)
 				n += 32;
 		}
+	}
 	return n - 1;
 }