Import LEDE dts files for Ralink/Mediatek
This is an import of the reworked LEDE dts files. Besides other things
they make it easier for us to reuse.
The only diffs left are for the following SoCs:
So we include the fbsd-*.dtsi files at the end of the original LEDE dtsi
files, using '#include "fbsd-xxxx.dtsi"'.
For example, for MT7621, the LEDE dtsi file is mt7621.dtsi. At the end of
it we add:
Approved by: adrian (mentor)
Obtained from: LEDE project
Sponsored by: Smartcom - Bulgaria AD
Differential Revision: https://reviews.freebsd.org/D6394