kirkwood: set default state for status LEDs in device tree

kirkwood: set default state for status LEDs in device tree

This adds the default-state = "on"; statement for the power or
primary status LED in DTS on kirkwood. This will ensure that this
LED will be lit up very early in the boot process (i.e. before
diag.sh is executed) and thus will provide an additional hint to the
user when problems arise during early boot process.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>