boards: add vendor to board yaml

This is coming from devicetree and corrosponds to what we have in the
dts/bindings/vendor-prefixes.txt file.

This will allow for static filtering, especially with twister, i.e. no
need to build anything to know the vendor of a board

All of the vendor data was extracted automatically from the devicetree,
so some platforms might not have the right vendor or no vendor at all
right now, we need to fix some of the DTS information or do this
manually to get this 100% correct. But we are close.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>