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/memory-failure.c b/mm/memory-failure.c
index 0207c2f..bfba796 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -945,7 +945,7 @@
 		collect_procs(ppage, &tokill);
 
 	if (hpage != ppage)
-		lock_page_nosync(ppage);
+		lock_page(ppage);
 
 	ret = try_to_unmap(ppage, ttu);
 	if (ret != SWAP_SUCCESS)
@@ -1038,7 +1038,7 @@
 			 * Check "just unpoisoned", "filter hit", and
 			 * "race with other subpage."
 			 */
-			lock_page_nosync(hpage);
+			lock_page(hpage);
 			if (!PageHWPoison(hpage)
 			    || (hwpoison_filter(p) && TestClearPageHWPoison(p))
 			    || (p != hpage && TestSetPageHWPoison(hpage))) {
@@ -1088,7 +1088,7 @@
 	 * It's very difficult to mess with pages currently under IO
 	 * and in many cases impossible, so we just avoid it here.
 	 */
-	lock_page_nosync(hpage);
+	lock_page(hpage);
 
 	/*
 	 * unpoison always clear PG_hwpoison inside page lock
@@ -1231,7 +1231,7 @@
 		return 0;
 	}
 
-	lock_page_nosync(page);
+	lock_page(page);
 	/*
 	 * This test is racy because PG_hwpoison is set outside of page lock.
 	 * That's acceptable because that won't trigger kernel panic. Instead,