bcm2708: Add extension to configure internal pulls

The bcm2708 gpio controller supports internal pulls to be used as pull-up,
pull-down or being entirely disabled. As it can be useful for a driver to
change the pull configuration from it's default pull-down state, add an
extension which allows configuring the pull per gpio.

Signed-off-by: Julian Scheel <julian@jusst.de>
lirc_rpi: Add parameter to specify input pin pull

Depending on the connected IR circuitry it might be desirable to change the
gpios internal pull from it pull-down default behaviour. Add a module
parameter to allow the user to set it explicitly.

Signed-off-by: Julian Scheel <julian@jusst.de>