gluon-setup-mode: set br-setup MAC address to the primary MAC address

This allows to reach the node in setup mode over the same link-local IPv6
address as br-client uses during normal operation.

package/gluon-setup-mode/files/lib/gluon/setup-mode/rc.d/S20network

@@ -26,6 +26,7 @@ prepare_config() {
 
 	uci_add network interface setup
 	uci_set network setup ifname "$(lua -e 'print(require("gluon.sysconfig").setup_ifname)')"
+	uci_set network setup macaddr "$(lua -e 'print(require("gluon.sysconfig").primary_mac)')"
 	uci_set network setup type 'bridge'
 	uci_set network setup proto 'static'
 	uci_set network setup ipaddr "$SETUP_MODE_ADDR"