ACPI / scan: Simplify acpi_bus_extract_wakeup_device_power_package()

acpi_bus_extract_wakeup_device_power_package() is a static function
with a single caller that supplies (device->handle, &device->wakeup).

Simplify the interface so the caller need only supply "device".

This makes it obvious that "wakeup", i.e., &device->wakeup, can never
be NULL, so remove the unnecessary check for that.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>