qcacmn: Fix TX Desc invalid accessing when process TX completion

In some corner case, host has done Vdev destroy and TX desc flush
since there is pending outstanding TX data on this vdev, but later
FW/HW still indicate the TX completion to host and which likely
these TX completion get delayed, conflict happened due to same TX
Desc accessing.

To fix it:
(1) Only reset TX desc Vdev to NULL in dp_tx_vdev_detach().
(2) Do more enhancement in dp_tx_comp_handler() to avoid
    invalid Vdev accessing.
(3) Do TX desc flush in dp_tx_pdev_detach().

Change-Id: I44cce9451e4f07fed6e21a9cd3fc0eaefa3d54c2
CRs-Fixed: 2441455

dp/wifi3.0/dp_tx_desc.h

@@ -301,6 +301,8 @@ dp_tx_desc_free(struct dp_soc *soc, struct dp_tx_desc_s *tx_desc,
 	enum netif_action_type act = WLAN_WAKE_ALL_NETIF_QUEUE;
 
 	qdf_spin_lock_bh(&pool->flow_pool_lock);
+	tx_desc->vdev = NULL;
+	tx_desc->nbuf = NULL;
 	tx_desc->flags = 0;
 	dp_tx_put_desc_flow_pool(pool, tx_desc);
 	switch (pool->status) {
@@ -456,6 +458,8 @@ dp_tx_desc_free(struct dp_soc *soc, struct dp_tx_desc_s *tx_desc,
 	struct dp_tx_desc_pool_s *pool = &soc->tx_desc[desc_pool_id];
 
 	qdf_spin_lock_bh(&pool->flow_pool_lock);
+	tx_desc->vdev = NULL;
+	tx_desc->nbuf = NULL;
 	tx_desc->flags = 0;
 	dp_tx_put_desc_flow_pool(pool, tx_desc);
 	switch (pool->status) {
@@ -510,7 +514,6 @@ dp_tx_desc_thresh_reached(struct cdp_vdev *vdev)
 
 	return  dp_tx_is_threshold_reached(pool, pool->avail_desc);
 }
-
 #else /* QCA_LL_TX_FLOW_CONTROL_V2 */
 
 static inline void dp_tx_flow_control_init(struct dp_soc *handle)