wlan: Fix dangling pAdapter pointer in HDD.

On getting response from FW , SME calls hdd in
hdd_tx_per_hit_cb with pAdapter as argument.But
by that pAdapter in hdd might be removed.
As a part of fix, instead of passing pAdapter,
sessionId is passed. So when SME gets response from
FW , it will call hdd with sessionId and in hdd based
on sessionId a valid pAdapter would be used.

Change-Id: I008f8be1792a389839966487eaef99dd108d1c8c
CRs-Fixed: 699843
diff --git a/CORE/HDD/src/wlan_hdd_wext.c b/CORE/HDD/src/wlan_hdd_wext.c
index e6aed4f..e9728e6 100644
--- a/CORE/HDD/src/wlan_hdd_wext.c
+++ b/CORE/HDD/src/wlan_hdd_wext.c
@@ -2398,7 +2398,7 @@
     unsigned char tx_fail[16];
     union iwreq_data wrqu;
 
-    if (NULL == pAdapter)
+    if (NULL == pAdapter || (WLAN_HDD_ADAPTER_MAGIC != pAdapter->magic))
     {
         hddLog(LOGE, "hdd_tx_per_hit_cb: pAdapter is NULL");
         return;