Staging: ipack: remove memory mapping callbacks.

Now that we have the infrastructure to use the regular function in place
and all existing users are converted, remove the map and unmap callbacks
from the ipack_bus_device->ops.

Signed-off-by: Jens Taprogge <jens.taprogge@taprogge.org>
Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>