cpu/x86/mtrr: Prepare for ROM_SIZE > 16MiB

Most, if not all, chipsets have MMIO between 0xfe000000 and 0xff000000.
So don't try to cache more than 16MiB of the ROM. It's also common that
at most 16MiB are memory mapped.

Change-Id: I5dfa2744190a34c56c86e108a8c50dca9d428268
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/26567
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

0 files changed, 0 insertions, 0 deletions