block: Remove useless IPI struct initialization

rq_fifo_clear() reset the csd.list through INIT_LIST_HEAD for no clear
purpose. The csd.list doesn't need to be initialized as a list head
because it's only ever used as a list node.

Lets remove this useless initialization.
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

include/linux/elevator.h

@@ -203,10 +203,7 @@ enum {
 #define rb_entry_rq(node)	rb_entry((node), struct request, rb_node)
 
 #define rq_entry_fifo(ptr)	list_entry((ptr), struct request, queuelist)
-#define rq_fifo_clear(rq)	do {		\
-	list_del_init(&(rq)->queuelist);	\
-	INIT_LIST_HEAD(&(rq)->csd.list);	\
-	} while (0)
+#define rq_fifo_clear(rq)	list_del_init(&(rq)->queuelist)
 
 #else /* CONFIG_BLOCK */