Long relative path for chip include

[CvRXX]

I don't really have a solution this but now users have to list quite a long path to select a chip. It would be cool if we could figure something out in cmake to make this easier.

How it's now:
include(${toolchain}/targets/arm32/cm4/nordic/nrf/nrf52/nrf52.cmake)

Would love something like this:
selectChip(nordic,nrf52)

@ManDeJan @cjsmeele hope you could figure this one out.