iwlwifi: mvm: inc pending frames counter also when txing non-sta

Until this patch, when TXing non-sta the pending_frames counter
wasn't increased, but it WAS decreased in
iwl_mvm_rx_tx_cmd_single(), what makes it negative in certain
conditions. This in turn caused much trouble when we need to
remove the station since we won't be waiting forever until
pending_frames gets 0. In certain cases, we were exhausting
the station table even in BSS mode, because we had a lot of
stale stations.

Increase the counter also in iwl_mvm_tx_skb_non_sta() after a
successful TX to avoid this outcome.

CC: <stable@vger.kernel.org> [3.18+]
Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/tx.c

@@ -423,6 +423,15 @@ int iwl_mvm_tx_skb_non_sta(struct iwl_mvm *mvm, struct sk_buff *skb)
 		return -1;
 	}
 
+	/*
+	 * Increase the pending frames counter, so that later when a reply comes
+	 * in and the counter is decreased - we don't start getting negative
+	 * values.
+	 * Note that we don't need to make sure it isn't agg'd, since we're
+	 * TXing non-sta
+	 */
+	atomic_inc(&mvm->pending_frames[sta_id]);
+
 	return 0;
 }