iwlwifi: tx_sync only on PAN context

Ted reported that he couldn't connect to some APs
and bisected it to the tx_sync implementation.
Disable it for the BSS context to fix this issue.
Reported-by: NTed Ts'o <tytso@mit.edu>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

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

@@ -2850,6 +2850,9 @@ static int iwlagn_mac_tx_sync(struct ieee80211_hw *hw,
 	int ret;
 	u8 sta_id;
 
+	if (ctx->ctxid != IWL_RXON_CTX_PAN)
+		return 0;
+
 	IWL_DEBUG_MAC80211(priv, "enter\n");
 	mutex_lock(&priv->shrd->mutex);
 
@@ -2898,6 +2901,9 @@ static void iwlagn_mac_finish_tx_sync(struct ieee80211_hw *hw,
 	struct iwl_vif_priv *vif_priv = (void *)vif->drv_priv;
 	struct iwl_rxon_context *ctx = vif_priv->ctx;
 
+	if (ctx->ctxid != IWL_RXON_CTX_PAN)
+		return;
+
 	IWL_DEBUG_MAC80211(priv, "enter\n");
 	mutex_lock(&priv->shrd->mutex);