mb/google/rex/variants/deku: Add GPIO configuration

Based on Platform Mapping Document for Deku (go/cros-deku-mapping)
from Nov 8, 2023 (Rev 0.4)

BUG=b:305793886
TEST=WIP, not tested yet

Change-Id: Ib37a7ebf0aca788d14fafea0f97e364beafb4c4d
Signed-off-by: Eran Mitrani <mitrani@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78960
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>