drbd: use DEFINE_SPINLOCK() for spinlock

spinlock can be initialized automatically with DEFINE_SPINLOCK()
rather than explicitly calling spin_lock_init().
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Guobin Huang <huangguobin4@huawei.com>
Link: https://lore.kernel.org/r/1617710988-49205-1-git-send-email-huangguobin4@huawei.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/drbd/drbd_main.c

@@ -125,7 +125,7 @@ struct bio_set drbd_io_bio_set;
 	 member of struct page.
  */
 struct page *drbd_pp_pool;
-spinlock_t   drbd_pp_lock;
+DEFINE_SPINLOCK(drbd_pp_lock);
 int          drbd_pp_vacant;
 wait_queue_head_t drbd_pp_wait;
 
@@ -2160,9 +2160,6 @@ static int drbd_create_mempools(void)
 	if (ret)
 		goto Enomem;
 
-	/* drbd's page pool */
-	spin_lock_init(&drbd_pp_lock);
-
 	for (i = 0; i < number; i++) {
 		page = alloc_page(GFP_HIGHUSER);
 		if (!page)