TDLS: Set tdls hdd context to NULL after freeing

While exiting the tdls hdd context after freeing the peer list
we should also set TDLS context in STA session context of adapter
to NULL.

CRs-Fixed: 637112
Change-Id: I5d8f99b74d1421434e28dc3d0a43dde306292fe3
diff --git a/CORE/HDD/src/wlan_hdd_tdls.c b/CORE/HDD/src/wlan_hdd_tdls.c
index 7fa2242..2a24cce 100644
--- a/CORE/HDD/src/wlan_hdd_tdls.c
+++ b/CORE/HDD/src/wlan_hdd_tdls.c
@@ -816,6 +816,7 @@
     wlan_hdd_tdls_free_scan_request(&pHddCtx->tdls_scan_ctxt);
 
     vos_mem_free(pHddTdlsCtx);
+    pAdapter->sessionCtx.station.pHddTdlsCtx = NULL;
     pHddTdlsCtx = NULL;
 }