ACPI: PM: s2idle: Drop unused local variables and related code

Two local variables in drivers/acpi/x86/s2idle.c are never read, so
drop them along with the code updating their values (in vain).

Fixes: fef98671 ("ACPI: PM: s2idle: Move x86-specific code to the x86 directory")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>