block: move blk-throtl fast path inline

Even if no policies are defined, we spend ~2% of the total IO time
checking. Move the fast path inline.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-core.c b/block/blk-core.c
index b08aed2..3b5ee3f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -50,6 +50,7 @@
 #include "blk-mq.h"
 #include "blk-mq-sched.h"
 #include "blk-pm.h"
+#include "blk-throttle.h"
 
 struct dentry *blk_debugfs_root;