nb/intel/haswell: Introduce option to not use MRC.bin

nb/intel/haswell: Introduce option to not use MRC.bin

Introduce the `USE_NATIVE_RAMINIT` Kconfig option, which should allow
booting coreboot on Haswell mainboards without the need of the closed
source MRC.bin. For now, this option does not work at all; the needed
magic will be implemented in subsequent commits. Add a config file to
make sure the newly-introduced option gets build-tested.

Change-Id: I46c77586f9b5771624082e07c60c205e578edd8e
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64176
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>