kirkwood/orion: fix orion_gpio_set_blink

gpio registers are for 32 gpios. Given that orion_gpio_set_blink is called
directly and not through gpiolib, it needs to make sure that the pin value
given to the internal functions are between 0 and 31.

Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Tested-By: Adam Baker <linux@baker-net.org.uk>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>