The linux list compat code had an error which prevented list_for_each_safe()

from operating on a list with a single item.  This code is used much more by
the i915 driver with xorg-7.4.  Correct it to match the actual linux
implementation.

Approved by:	jhb (mentor)

sys/dev/drm/drm_linux_list.h

@@ -69,6 +69,6 @@ list_del(struct list_head *entry) {
 
 #define list_for_each_safe(entry, temp, head)			\
     for (entry = (head)->next, temp = (entry)->next;		\
-	temp != head; 						\
-	entry = temp, temp = temp->next)
+	entry != head; 						\
+	entry = temp, temp = entry->next)