blk-mq: divert __blk_put_request for MQ ops

__blk_put_request needs to call into the blk-mq code just like
blk_put_request.  As we don't have the queue lock in this case both
end up calling the same function.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index c00e0bd..06636f3 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1278,6 +1278,11 @@
 	if (unlikely(!q))
 		return;
 
+	if (q->mq_ops) {
+		blk_mq_free_request(req);
+		return;
+	}
+
 	blk_pm_put_request(req);
 
 	elv_completed_request(q, req);