blk-mq: rename blk_mq_hw_ctx->queue_rq_srcu to ->srcu

The RCU protection has been expanded to cover both queueing and
completion paths making ->queue_rq_srcu a misnomer.  Rename it to
->srcu as suggested by Bart.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 460798d..8efcf49 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -66,7 +66,7 @@
 #endif
 
 	/* Must be the last member - see also blk_mq_hw_ctx_size(). */
-	struct srcu_struct	queue_rq_srcu[0];
+	struct srcu_struct	srcu[0];
 };
 
 struct blk_mq_tag_set {