wireless: Use macro instead of number

Use IEEE80211_MIN_ACTION_SIZE macro for robust management frame check.

Signed-off-by: Masashi Honma <masashi.honma@gmail.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index b118744..1daebb3 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -2464,7 +2464,7 @@
  */
 static inline bool ieee80211_is_robust_mgmt_frame(struct sk_buff *skb)
 {
-	if (skb->len < 25)
+	if (skb->len < IEEE80211_MIN_ACTION_SIZE)
 		return false;
 	return _ieee80211_is_robust_mgmt_frame((void *)skb->data);
 }