sb,soc/intel: Add wake source fields in GNVS

sb,soc/intel: Add wake source fields in GNVS

For the moment, these are most not used but become a necessity
for a unified <soc/nvs.h> approach.

They would be required for the implementation of _SWS method
for OSPM to determine the reason for system waking up. The related
hardware registers are present with these platforms.

It's expected that ACPI power-management related GNVS entries are
grouped together to form a single struct in later works.

Change-Id: I6d31d39ac1017cd6fdf0ac66b418d1fbb1edf8e0
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50193
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>