qcacld-3.0: Fix pointer dereference condition

In the API hdd_update_tgt_cfg, the driver extracts hdd_ctx from
context, and it may happen that the context is NULL, which may cause
pointer dereference in the same API

Fix is to have a NULL check for hdd_ctx

Change-Id: I9216e0fb72d1825af10445c52448c102603f7e13
CRs-Fixed: 2259401

core/hdd/src/wlan_hdd_main.c

@@ -1889,6 +1889,10 @@ void hdd_update_tgt_cfg(hdd_handle_t hdd_handle, struct wma_tgt_cfg *cfg)
 	QDF_STATUS status;
 	mac_handle_t mac_handle;
 
+	if (!hdd_ctx) {
+		hdd_err("HDD context is NULL");
+		return;
+	}
 	ret = hdd_objmgr_create_and_store_pdev(hdd_ctx);
 	if (ret) {
 		hdd_err("Failed to create pdev; errno:%d", ret);