drm: cleanup use of Linux list handling macros

This makes the drms use of the list handling macros a lot cleaner
and more along the lines of how they should be used and uses them
in some more places.

Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/char/drm/via_verifier.c b/drivers/char/drm/via_verifier.c
index 2e7e080..8b4ea30 100644
--- a/drivers/char/drm/via_verifier.c
+++ b/drivers/char/drm/via_verifier.c
@@ -254,7 +254,6 @@
 						    unsigned long size,
 						    drm_device_t * dev)
 {
-	struct list_head *list;
 	drm_map_list_t *r_list;
 	drm_local_map_t *map = seq->map_cache;
 
@@ -263,8 +262,7 @@
 		return map;
 	}
 
-	list_for_each(list, &dev->maplist->head) {
-		r_list = (drm_map_list_t *) list;
+	list_for_each_entry(r_list, &dev->maplist, head) {
 		map = r_list->map;
 		if (!map)
 			continue;