ath79: teltonika-rut230: add RUT240 model alias

Define RUT240 as alternative name, to explicitly show the device is
supported using existing image.

Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
Link: openwrt#17503
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

target/linux/ath79/image/generic.mk

@@ -3063,6 +3063,9 @@ define Device/teltonika_rut230-v1
   DEVICE_VENDOR := Teltonika
   DEVICE_MODEL := RUT230
   DEVICE_VARIANT := v1
+  DEVICE_ALT0_VENDOR := Teltonika
+  DEVICE_ALT0_MODEL := RUT240
+  DEVICE_ALT0_VARIANT := v1
   DEVICE_PACKAGES := kmod-usb2 kmod-usb-chipidea2 kmod-usb-acm \
 	kmod-usb-net-qmi-wwan kmod-usb-serial-option uqmi -uboot-envtools
   IMAGE_SIZE := 15552k