[coreboot] v3 CAR/ROM area collision on C7 and Core2Duo

[Carl-Daniel Hailfinger]

Hi,

in v2 we enable full ROM decoding before initram. For VIA C7 and Intel
Core 2 Duo, that means the CAR area is inside the mapped ROM contents.

The most obvious problem arising from that is having to make sure
fallback/initram and normal/initram end up in a place in ROM that is
_not_ behind CAR.

One solution is to restrict the location of initram to the upper 1 MB of
the ROM chip. I can work with that, but we should definitely document
these restrictions.

Oh, and for chips which are behind some translation unit with limited
window capabilities (like the IT8716 LPC->SPI translation) we need to
have initram inside the decoded window anyway.

Regards,
Carl-Daniel