Device interface & MIDDrv should allow to set up volume & pan

[Raffaello]

to set up the volume for OPL for e.g. it is required to retrieve the OPL Mixer channel and its sound handle.

instead would be a lot simpler if it that channel can be manipulated directly through the device interface.

and therefore the MIDDrv can also be used to interact with the device to change the volume