leds: apu: drop enum_apu_led_platform_types

As this driver now only supports the APU1 boards, we don't need
to differenciate between board types anymore. Therefore optimize
away the now obsolete code.

Signed-off-by: Enrico Weigelt <info@metux.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>