Add some basic chanctx implementation - debug prints,
and save the vif's channel/band/type.

After that, we no longer need to handle channel change
notifications on op_config.
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>