define it with a single variable, rather than several.

this allows several checks to be greatly simplified.

Signed-off-by: Leah Rowe <leah@libreboot.org>

This is similar to the 9020SFF, but this board has ECC support.
However, the native raminit isn't used here, even though it is
otherwise compatible, because the native init doesn't do ECC yet.

The broadwell mrc.bin has ECC support, which is also used on the
HP EliteBook 820 G2. The MRC for broadwell can be used on haswell
boards such as the T1700.

Add both the SFF and MT variants. Since these are identical to the
9020 variants, except for slightly different PCH enabling ECC, we
can just re-use the 9020 port without issue.

We *could* add a variant to coreboot, for T1700, but there is not
really any pressing need. It is simply the 9020sff/mt with mrc.bin

Signed-off-by: Leah Rowe <leah@libreboot.org>