mainboard/google/kahlee: Update memory.c

This fixes some issues with the initial implementation that was copied
from reef.
- The board ID value shouldn't be size_t - it's not a size.
- Kahlee doesn't even need the memory.c file - it uses an SoDIMM.

BUG=b:68293392
TEST=build stoney platforms, boot kahleebo

Change-Id: Ife5660d36912e887edfd0365a9f16c5a172c9c86
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/22515
Reviewed-by: Marc Jones <marc@marcjonesconsulting.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
4 files changed