nl80211: Move peer link state definition to nl80211

These definitions need to be exposed now that we can set the peer link
states via NL80211_ATTR_STA_PLINK_STATE.  They were already being
(opaquely) reported by NL80211_STA_INFO_PLINK_STATE.

Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 1b9413f..3a9515c 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -490,7 +490,7 @@
 	 * establisment frame, beacon or probe, drop the frame.
 	 */
 
-	if (!rx->sta || sta_plink_state(rx->sta) != PLINK_ESTAB) {
+	if (!rx->sta || sta_plink_state(rx->sta) != NL80211_PLINK_ESTAB) {
 		struct ieee80211_mgmt *mgmt;
 
 		if (!ieee80211_is_mgmt(hdr->frame_control))