remove board: d945gclf

these boards are almost impossible to find, and have always been
buggy, it doesn't look like there will be any viable testing or
development on it

it's currently broken in master, on coreboot. if someone wants to
fix and re-add to lbmk, they can do that

use older libreboot releases to flash this board, if you wish

(i *am* adding te the issue tracker, a note about this commit,
with a view to re-adding it one day)