block: move ->timeout request member

After the recent timeout handling changes, we have two holes in
the struct. Move the timeout near the deadline, killing both,
and moving related members closer together. On my config on
x86-64, this shrinks struct request from 312 to 304 bytes.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/blkdev.h

@@ -237,15 +237,15 @@ struct request {
 	unsigned short write_hint;
 	unsigned short ioprio;
 
-	unsigned int timeout;
-
 	void *special;		/* opaque pointer available for LLD use */
 
 	unsigned int extra_len;	/* length of alignment and padding */
 
 	enum mq_rq_state state;
 	refcount_t ref;
 
+	unsigned int timeout;
+
 	/* access through blk_rq_set_deadline, blk_rq_deadline */
 	unsigned long __deadline;