[coreboot] [PATCH]more kconfig

[Patrick Georgi]

Hi,

attached patch enables kconfig based builds for a couple more boards. As
usual, this merely passes build and a validity check that all variables
are defined that are defined by newconfig (but not necessarily the same
value).

The larger part of this (which is why I stopped porting more boards and
want to get this out first) is that I moved the -O2 flag for romcc
invocations into ROMCCFLAGS, as rca/rm4100 wants -O only.

Signed-off-by: Patrick Georgi