sb/intel/gpio: Cache gpiobase in ramstage and romstage

Implement caching like it's done with pmbase.

Change-Id: I26d56a9ff1a8d6e64c164f36e23b846b8b459380
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/27664
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2 files changed