ACPI / PM: Sanitize checks in acpi_power_on_resources()

After the only user of acpi_power_on_resources(),
acpi_bus_init_power(), has been changed to avoid calling it
for state equal to ACPI_STATE_D3_COLD, it doesn't have to special
case that state any more.

For this reason, modify the checks in acpi_power_on_resources()
so that it returns -EINVAL for ACPI_STATE_D3_COLD as it should.

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