mwl8k: recheck if station still has valid rates

We have 6.5 Mbps is minimum rate of the link
as the criterion for creation of BA.

Although we check this before creating the BA
stream, by the time amdpu_action is called from
the workqueue, the link can get affected in the
meantime.
Hence, add an additional check in amdpu_action.
Signed-off-by: Yogesh Ashok Powar <yogeshp@marvell.com>
Signed-off-by: Nishant Sarmukadam <nishants@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwl8k.c

@@ -5085,6 +5085,7 @@ mwl8k_ampdu_action(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 	struct mwl8k_priv *priv = hw->priv;
 	struct mwl8k_ampdu_stream *stream;
 	u8 *addr = sta->addr;
+	struct mwl8k_sta *sta_info = MWL8K_STA(sta);
 
 	if (!(hw->flags & IEEE80211_HW_AMPDU_AGGREGATION))
 		return -ENOTSUPP;
@@ -5127,6 +5128,15 @@ mwl8k_ampdu_action(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		/* Release the lock before we do the time consuming stuff */
 		spin_unlock(&priv->stream_lock);
 		for (i = 0; i < MAX_AMPDU_ATTEMPTS; i++) {
+
+			/* Check if link is still valid */
+			if (!sta_info->is_ampdu_allowed) {
+				spin_lock(&priv->stream_lock);
+				mwl8k_remove_stream(hw, stream);
+				spin_unlock(&priv->stream_lock);
+				return -EBUSY;
+			}
+
 			rc = mwl8k_check_ba(hw, stream);
 
 			/* If HW restart is in progress mwl8k_post_cmd will