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/fs/nilfs2/btnode.c b/fs/nilfs2/btnode.c
index 388e9e8..f4f1c08 100644
--- a/fs/nilfs2/btnode.c
+++ b/fs/nilfs2/btnode.c
@@ -40,14 +40,10 @@
 	nilfs_mapping_init_once(btnc);
 }
 
-static const struct address_space_operations def_btnode_aops = {
-	.sync_page		= block_sync_page,
-};
-
 void nilfs_btnode_cache_init(struct address_space *btnc,
 			     struct backing_dev_info *bdi)
 {
-	nilfs_mapping_init(btnc, bdi, &def_btnode_aops);
+	nilfs_mapping_init(btnc, bdi);
 }
 
 void nilfs_btnode_cache_clear(struct address_space *btnc)