block: remove per-queue plugging

Code has been converted over to the new explicit on-stack plugging,
and delay users have been converted to use the new API for that.
So lets kill off the old plugging along with aops->sync_page().

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 2cb01f6..cc0ede1 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1239,7 +1239,7 @@
 {
 	int ret;
 
-	lock_page_nosync(page);
+	lock_page(page);
 	ret = set_page_dirty(page);
 	unlock_page(page);
 	return ret;