ACPI / PM: Export acpi_device_fix_up_power()

Drivers that needs acpi_device_fix_up_power(), allow them to be built as
modules by exporting this function.

Cc: <stable@vger.kernel.org> # 4.5+
Tested-by: Laszlo Fiat <laszlo.fiat@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>