timerqueue: Use rb_entry_safe() instead of open-coding it

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/0d5cf199ac43792df0b6f7e2145545c30fa1dbbe.1482222135.git.geliangtang@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

lib/timerqueue.c

@@ -80,8 +80,7 @@ bool timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
 	if (head->next == node) {
 		struct rb_node *rbn = rb_next(&node->node);
 
-		head->next = rbn ?
-			rb_entry(rbn, struct timerqueue_node, node) : NULL;
+		head->next = rb_entry_safe(rbn, struct timerqueue_node, node);
 	}
 	rb_erase(&node->node, &head->head);
 	RB_CLEAR_NODE(&node->node);