ocfs2: use cond_resched() in dlm_thread()

yield() does not yield.  cond_resched() does.
Signed-off-by: Kurt Hackel <kurt.hackel@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

fs/ocfs2/dlm/dlmthread.c

@@ -731,7 +731,7 @@ static int dlm_thread(void *data)
 
 		/* yield and continue right away if there is more work to do */
 		if (!n) {
-			yield();
+			cond_resched();
 			continue;
 		}