block/drbd: delete invalid function drbd_md_mark_dirty_

We deleted last_md_mark_dirty long ago, this function no longer needs to
exist, delete it, otherwise a compilation error will occur when DEBUG is
opened.

Fixes: ac0acb9e ("drbd: use drbd_device_post_work() in more place")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/drbd/drbd_main.c

@@ -3414,22 +3414,11 @@ int drbd_md_read(struct drbd_device *device, struct drbd_backing_dev *bdev)
  * the meta-data super block. This function sets MD_DIRTY, and starts a
  * timer that ensures that within five seconds you have to call drbd_md_sync().
  */
-#ifdef DEBUG
-void drbd_md_mark_dirty_(struct drbd_device *device, unsigned int line, const char *func)
-{
-	if (!test_and_set_bit(MD_DIRTY, &device->flags)) {
-		mod_timer(&device->md_sync_timer, jiffies + HZ);
-		device->last_md_mark_dirty.line = line;
-		device->last_md_mark_dirty.func = func;
-	}
-}
-#else
 void drbd_md_mark_dirty(struct drbd_device *device)
 {
 	if (!test_and_set_bit(MD_DIRTY, &device->flags))
 		mod_timer(&device->md_sync_timer, jiffies + 5*HZ);
 }
-#endif
 
 void drbd_uuid_move_history(struct drbd_device *device) __must_hold(local)
 {