ctlra: rework screen impl for multiple screens
ctlra: rework screen impl for multiple screens

Both of the maschine3 screens now have callbacks called
as the correct internal get_data() function is used.

Signed-off-by: Harry van Haaren <6e1296516ee88185cd60d9725251227ece1af74d@gmail.com>

openAVproductions/openAV-Ctlra