atusd.brd: increased via density in RF areas
atusd.brd: increased via density in RF areas

- atusd.brd: moved antenna by 20 mil to make more room for vias
- atusd.brd: increased RF via density to up to 50-60 mil per via
- atusd.brd: increased zone clearance to 10 mil, to make board easier to
  solder

cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan