ACPI: Let the parser return false for disabled resources

If the parser disables a resource during parsing, let it return false,
so the calling code does not need to implement further checks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>