Support for nRF5340

[PasVegan]

Hi,

I am using the nRF5340 DK along with an RGB module that has 8 NeoPixels. I tried to use it with this board without the library but was unsuccessful. Could you add support for this board or guide me on how to make this library work with it?

Thank you very much!

[ladyada]

a PR from someone who has the hardware is welcome!