x86/platform/geode: Convert alix LED to GPIO machine descriptor

Look up the LED from a GPIO machine descriptor table. The Geode LEDs
should be on the CS5535 companion chip.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lkml.kernel.org/r/20201124085339.6181-3-linus.walleij@linaro.org