aout: remove choices list on the device variable
aout: remove choices list on the device variable

This does not support hot plug and unplug of devices.

Also, it prevented selecting a device not in the choices list due to
checks in the variables subsystem. (At least with ALSA, not all valid
devices are included in the suggestions.)

vlc-mirror/vlc-2.1,shyamalschandra/vlc,krichter722/vlc,jomanmuk/vlc-2.2,shyamalschandra/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,xkfz007/vlc,krichter722/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,krichter722/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,shyamalschandra/vlc,jomanmuk/vlc-2.1,xkfz007/vlc,krichter722/vlc,vlc-mirror/vlc-2.1,krichter722/vlc,shyamalschandra/vlc,vlc-mirror/vlc-2.1,xkfz007/vlc,xkfz007/vlc,vlc-mirror/vlc,xkfz007/vlc,shyamalschandra/vlc,vlc-mirror/vlc,vlc-mirror/vlc,xkfz007/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc,krichter722/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.2,vlc-mirror/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,krichter722/vlc,vlc-mirror/vlc-2.1,vlc-mirror/vlc,xkfz007/vlc,shyamalschandra/vlc,vlc-mirror/vlc,jomanmuk/vlc-2.2