qcacld-3.0: Validate KCK pointer in GTK Rekey data

For FILS based authentication, KCK is not derived. Hence
when GTK Offload feature is enabled, supplicant will not
pass it to driver with gtk rekey data. Putting a check
to validate KCK before copying it to the gtk_req structure.

Change-Id: I7089011b4d3fdc4e4785adbe10de651a1b59a121
CRs-Fixed: 2414445

core/hdd/src/wlan_hdd_cfg80211.c

@@ -20171,7 +20171,8 @@ int __wlan_hdd_cfg80211_set_rekey_data(struct wiphy *wiphy,
 		gtk_req->replay_counter);
 
 	wlan_hdd_copy_gtk_kek(gtk_req, data);
-	qdf_mem_copy(gtk_req->kck, data->kck, NL80211_KCK_LEN);
+	if (data->kck)
+		qdf_mem_copy(gtk_req->kck, data->kck, NL80211_KCK_LEN);
 	gtk_req->is_fils_connection = hdd_is_fils_connection(adapter);
 	vdev = hdd_objmgr_get_vdev(adapter);
 	if (!vdev) {