Add GBTR Method, which gets the state of the RF Kill pin. Unlike
the VGPIO, this can be used for both CNVi and full PCI wireless
cards.
Change-Id: I8d025f63192218399b8d5e60e847853e54a8353c
Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/84992
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nicholas Sudsgaard <devel+coreboot@nsudsgaard.com>