Adding device support for Teltonika RUTXR1

List of additional files included in the Teltonika firmware -
https://pastie.io/mcadjy.groovy

I did a quick check between the Teltonika SDK target and the latest OpenWrt target.

It doesn't seem to reference a DTS file for the Teltonika RUTX exactly however doing a build of the Teltonika firmware and searching the build_target folder provides the qcom-ipq4018-rutx.dts & qcom-ipq4018-rutx.dtb

It looks like the Teltonika SDK is based off of the 19.07.04 version of OpenWrt.