cfg80211.h uses struct nla_policy in two places, but does not include 
net/netlink.h directly. Because of this missing include the rename to 
struct nla_backport_policy is not applied and this results in type 
mismatch errors when compiling backports. With this additional include 
the type is renamed.

--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -21,6 +21,7 @@
 #include <linux/ieee80211.h>
 #include <linux/net.h>
 #include <net/regulatory.h>
+#include <net/netlink.h>
 
 /**
  * DOC: Introduction