leds: apu: drop iosize field from priv data

As this driver now only supports the APU1 boards, we don't need
to handle different io sizes anymore.

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