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>

fs/nilfs2/gcinode.c

@@ -49,7 +49,6 @@
 #include "ifile.h"
 
 static const struct address_space_operations def_gcinode_aops = {
-	.sync_page		= block_sync_page,
 };
 
 /*