qcacld-3.0: Validate wma handle before using it

Validate wma handle before using it.

Change-Id: Ic8d62ffa66ace75ef43326908ad4ebe19cb8533a
CRs-Fixed: 2669309

core/wma/src/wma_utils.c

@@ -4425,6 +4425,10 @@ QDF_STATUS wma_sta_mlme_vdev_start_continue(struct vdev_mlme_obj *vdev_mlme,
 	tp_wma_handle wma = cds_get_context(QDF_MODULE_ID_WMA);
 	enum vdev_assoc_type assoc_type;
 
+	if (!wma) {
+		wma_err("Invalid wma handle");
+		return QDF_STATUS_E_FAILURE;
+	}
 	if (mlme_is_chan_switch_in_progress(vdev_mlme->vdev)) {
 		mlme_set_chan_switch_in_progress(vdev_mlme->vdev, false);
 		lim_process_switch_channel_rsp(wma->mac_context, data);