mmc: name mmc queue thread by host index

Usually there are multiple mmc host controllers; rename mmc queue thread
by host index so we can easily identify which controller it belongs to.
Signed-off-by: Ethan Du <ethan.too@gmail.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/card/queue.c

@@ -210,7 +210,9 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock
 
 	sema_init(&mq->thread_sem, 1);
 
-	mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd");
+	mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd/%d",
+		host->index);
+
 	if (IS_ERR(mq->thread)) {
 		ret = PTR_ERR(mq->thread);
 		goto free_bounce_sg;