taint: add explicit flag to show whether lock dep is still OK.

Fix up all callers as they were before, with make one change: an
unsigned module taints the kernel, but doesn't turn off lockdep.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index df2022f..4c99cb7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -320,7 +320,7 @@
 out:
 	/* Leave bad fields for debug, except PageBuddy could make trouble */
 	reset_page_mapcount(page); /* remove PageBuddy */
-	add_taint(TAINT_BAD_PAGE);
+	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 }
 
 /*