platform/x86/uniwill: Implement cTGP setting

Uniwill offers user setable cTGP for their EC on devices using NVIDIA 3000
Series and newer GPUs. This patch implements this setting as a sysfs
attribute.

For one device, the TUXEDO InfinityBook Gen7, the variant with and without
NVIDIA GPU can't be differentiated using only the DMI strings, so the new
probe callback needs to be used to test a bit from the EC memory.

Co-developed-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Link: https://patch.msgid.link/20260115154332.402873-2-wse@tuxedocomputers.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: tuxedo-wse