arm: kirkwood: sheevaplug: move pinmux configs to the right devices

When the pinmux mechanism was added in Kirkwood, the device driver
core was not yet providing the possibility of attaching pinmux
configurations to all devices, drivers had to do it explicitly, and
not all drivers were doing this.

Now that the driver core does that in a generic way, it makes sense to
attach the pinmux configuration to their corresponding devices.

Signed-off-by: Simon Baatz <gmbnomis@gmail.com>
Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>