Try this one, dont forget to flash openwrt-ar71xx-generic-rut200-squashfs-factory.bin not sysupgrade.
define Device/rut200
DEVICE_TITLE := Teltonika RUT200
DEVICE_PACKAGES := kmod-usb-core kmod-usb2 -uboot-envtools
BOARDNAME := RUT200
SUPPORTED_DEVICES := rut200
IMAGE_SIZE := 15552k
MTDPARTS := spi0.0:128k(u-boot)ro,64k(config)ro,64k(art)ro,15552k(firmware),576k(event-log)ro
TPLINK_HWID := 0x32200002
TPLINK_HWREV := 0x1
TPLINK_HEADER_VERSION := 1
CONSOLE := ttyATH0,115200
REVISION := RUT2xx
KERNEL := kernel-bin | patch-cmdline | lzma | tplink-v1-header
KERNEL_INITRAMFS := kernel-bin | patch-cmdline | lzma | uImage lzma
IMAGES := sysupgrade.bin factory.bin
IMAGE/factory.bin := append-kernel | pad-to $$$$(BLOCKSIZE) | append-rootfs |\
pad-rootfs | teltonika-fw-fake-checksum | append-string RUT200019999 | append-string master |\
append-md5sum-bin | check-size $$$$(IMAGE_SIZE)
IMAGE/sysupgrade.bin := append-kernel | pad-to $$$$(BLOCKSIZE) |\
append-rootfs | pad-rootfs | append-metadata |\
check-size $$$$(IMAGE_SIZE)
endef
TARGET_DEVICES += rut200