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/swap_state.c b/mm/swap_state.c
index 5c8cfab..46680461 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -24,12 +24,10 @@
 
 /*
  * swapper_space is a fiction, retained to simplify the path through
- * vmscan's shrink_page_list, to make sync_page look nicer, and to allow
- * future use of radix_tree tags in the swap cache.
+ * vmscan's shrink_page_list.
  */
 static const struct address_space_operations swap_aops = {
 	.writepage	= swap_writepage,
-	.sync_page	= block_sync_page,
 	.set_page_dirty	= __set_page_dirty_nobuffers,
 	.migratepage	= migrate_page,
 };
@@ -37,7 +35,6 @@
 static struct backing_dev_info swap_backing_dev_info = {
 	.name		= "swap",
 	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
-	.unplug_io_fn	= swap_unplug_io_fn,
 };
 
 struct address_space swapper_space = {