block: Fix throtl_pending_timer_fn() kernel-doc header

Commit e99e88a renamed a function argument without updating the
corresponding kernel-doc header. Update the kernel-doc header.

Reviewed-by: Chaitanya Kulkarni <chiatanya.kulkarni@wdc.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Fixes: e99e88a ("treewide: setup_timer() -> timer_setup()") # v4.15.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-throttle.c

@@ -1220,7 +1220,7 @@ static bool throtl_can_upgrade(struct throtl_data *td,
 	struct throtl_grp *this_tg);
 /**
  * throtl_pending_timer_fn - timer function for service_queue->pending_timer
- * @arg: the throtl_service_queue being serviced
+ * @t: the pending_timer member of the throtl_service_queue being serviced
  *
  * This timer is armed when a child throtl_grp with active bio's become
  * pending and queued on the service_queue's pending_tree and expires when