blk-mq: mark __blk_mq_complete_request() static

It's no longer used outside of blk-mq core.
Signed-off-by: Jens Axboe <axboe@fb.com>

block/blk-mq.c

@@ -358,7 +358,7 @@ static void blk_mq_ipi_complete_request(struct request *rq)
 	put_cpu();
 }
 
-void __blk_mq_complete_request(struct request *rq)
+static void __blk_mq_complete_request(struct request *rq)
 {
 	struct request_queue *q = rq->q;
 

block/blk-mq.h

@@ -25,7 +25,6 @@ struct blk_mq_ctx {
 	struct kobject		kobj;
 } ____cacheline_aligned_in_smp;
 
-void __blk_mq_complete_request(struct request *rq);
 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
 void blk_mq_freeze_queue(struct request_queue *q);
 void blk_mq_free_queue(struct request_queue *q);