mainboards: Drop PWRS from GNVS

Initialize variable to 1 to indicate AC power supply.
If platform has EC it will set this correctly based on
whether plugged on the charger or not.

Change-Id: I3f834cf7563b9e512fcab34cdb7a27a9f0fd31c0
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49352
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/acpi/dsdt_top.asl

@@ -7,3 +7,6 @@
 #include <vendorcode/google/chromeos/acpi/gnvs.asl>
 #include <vendorcode/google/chromeos/acpi/chromeos.asl>
 #endif
+
+/* Power state (AC = 1) */
+Name (PWRS, One)