[BLOCK] Get rid of request_queue_t typedef

Some of the code has been gradually transitioned to using the proper
struct request_queue, but there's lots left. So do a full sweet of
the kernel and get rid of this typedef and replace its uses with
the proper type.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/Documentation/iostats.txt b/Documentation/iostats.txt
index 09a1baf..b963c3b 100644
--- a/Documentation/iostats.txt
+++ b/Documentation/iostats.txt
@@ -79,7 +79,7 @@
     measured from __make_request() to end_that_request_last()).
 Field  9 -- # of I/Os currently in progress
     The only field that should go to zero. Incremented as requests are
-    given to appropriate request_queue_t and decremented as they finish.
+    given to appropriate struct request_queue and decremented as they finish.
 Field 10 -- # of milliseconds spent doing I/Os
     This field is increases so long as field 9 is nonzero.
 Field 11 -- weighted # of milliseconds spent doing I/Os