[ARM] Kirkwood: Export GPIO indicating jumper setting of JP1

Export GPIO 45 which is used to indicate the setting of the JP1
jumper.  This is useful for userland tools, such as qcontrol, to
see whether the LCD or a serial console is connected.

Signed-off-by: Martin Michlmayr <tbm@cyrius.com>
Signed-off-by: Nicolas Pitre <nico@fluxnic.net>