Add back the device mac_address field

Looks like this was accidentally removed during the
oclif refactor of `balena device`

Change-type: patch
See: https://github.com/balena-io/balena-cli/pull/1871
Signed-off-by: Thodoris Greasidis <thodoris@balena.io>

lib/actions-oclif/device/index.ts

@@ -94,6 +94,7 @@ export default class DeviceCmd extends Command {
 				'status',
 				'is_online',
 				'ip_address',
+				'mac_address',
 				'application_name',
 				'last_seen',
 				'uuid',