uhost_u1a: Add a leds_para section for the powerled

The powerled is controllable through gpio, so make it available for other uses.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
cubieboard[_512]: Turn on the green led by default

This is what Android does and was requested to me by a Fedora user, as it
shows that uboot has successfully loaded the kernel and the kernel is
running.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>