[coreboot] alix 2d2

[Jens Rottmann]

> Since the change is so small, how about we just add a Kconfig option
> to select the 2D2 variant of the board.

Or handle this even simpler yet: put both table entries for devices 0A
_and_ 0E in, increase IRQ_SLOT_COUNT to 7 and call the thing ALIX 2Dx.

AFAIK an IRQ routing table entry gets ignored anyway if the appropriate
device is not there, so the extra entry won't hurt either variant.

Cheers,
Jens