broadwell: Decouple LPDDR3 DQ/DQS maps from `pei_data`
Introduce the `BROADWELL_LPDDR3` Kconfig option along with some wrapper
code to allow mainboards using LPDDR3 DRAM to supply the DQ/DQS maps to
chipset code without having to use `pei_data`. The only mainboard using
LPDDR3 is Google Samus.
Change-Id: I0aaf0ace243c03600430c2a7ab6389a7b20cb432
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55812
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>