FROMGIT: block/blk-rq-qos: Move a function from a header file into a C file

rq_qos_id_to_name() is only used in blk-mq-debugfs.c so move that function
into in blk-mq-debugfs.c.

Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
BUG: 187357408
Change-Id: If03083a13917bc2f88b6df7151e033a11ab1bc50
(cherry picked from commit f1a7f539c2720906fb10be0af3514b034e1a9fee git://git.kernel.dk/linux-block/ for-5.14/block)
Signed-off-by: Bart Van Assche <bvanassche@google.com>
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 4de03da..7811bd7 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -939,6 +939,19 @@ void blk_mq_debugfs_unregister_sched(struct request_queue *q)
 	q->sched_debugfs_dir = NULL;
 }
 
+static const char *rq_qos_id_to_name(enum rq_qos_id id)
+{
+	switch (id) {
+	case RQ_QOS_WBT:
+		return "wbt";
+	case RQ_QOS_LATENCY:
+		return "latency";
+	case RQ_QOS_COST:
+		return "cost";
+	}
+	return "unknown";
+}
+
 void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos)
 {
 	debugfs_remove_recursive(rqos->debugfs_dir);