ARM: mach-shmobile: mackerel: Add LEDs support

you can control it by
echo 0 > /sys/class/leds/led0/brightness
echo 1 > /sys/class/leds/led0/brightness

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>