writeback: remove unnecessary init_timer call

The 'setup_timer()' function also calls 'init_timer()', so the extra
'init_timer()' call is not needed. Indeed, 'setup_timer()' is basically
'init_timer()' plus callback function and data pointers initialization.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

mm/backing-dev.c

@@ -236,7 +236,6 @@ static int __init default_bdi_init(void)
 	sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers");
 	BUG_ON(IS_ERR(sync_supers_tsk));
 
-	init_timer(&sync_supers_timer);
 	setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0);
 	bdi_arm_supers_timer();