iwlwifi: simplify code in iwlagn_key_sta_id

Simplify the code by returning directly in the
error case and replacing the switch/if with a
single if statement.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-agn-sta.c

@@ -1080,32 +1080,19 @@ static u8 iwlagn_key_sta_id(struct iwl_priv *priv,
 			    struct ieee80211_sta *sta)
 {
 	struct iwl_vif_priv *vif_priv = (void *)vif->drv_priv;
-	u8 sta_id = IWL_INVALID_STATION;
 
 	if (sta)
-		sta_id = iwl_sta_id(sta);
+		return iwl_sta_id(sta);
 
 	/*
 	 * The device expects GTKs for station interfaces to be
 	 * installed as GTKs for the AP station. If we have no
 	 * station ID, then use the ap_sta_id in that case.
 	 */
-	if (!sta && vif && vif_priv->ctx) {
-		switch (vif->type) {
-		case NL80211_IFTYPE_STATION:
-			sta_id = vif_priv->ctx->ap_sta_id;
-			break;
-		default:
-			/*
-			 * In all other cases, the key will be
-			 * used either for TX only or is bound
-			 * to a station already.
-			 */
-			break;
-		}
-	}
+	if (vif->type == NL80211_IFTYPE_STATION && vif_priv->ctx)
+		return vif_priv->ctx->ap_sta_id;
 
-	return sta_id;
+	return IWL_INVALID_STATION;
 }
 
 static int iwlagn_send_sta_key(struct iwl_priv *priv,