Cannot select SPDIF output

[riban-bw]

• Select Input Device = spdif
• Select Output Device = spdif
  Cannot select.
• Select Output Device = AoIP
• Select Output Device = spdif
  Can select.

[martim01]

The raspberry pi HATs don't seem to be able to handle input and ouput at the same time on the same card, at least not reliably.
Therefore I've made it that you can't select spdif as an output if spdif is an input

[riban-bw]

It appears possible to do it in the GUI, even if it doesn't work. Maybe disable or hide button to indicate it isn't available.