Right now this check is rejecting devices whose UCM config specifies
neither a conflicting device nor a supported device list, and accepting
devices which specify both. However, a device without neither list is
actually unrestricted, and a device with both lists is a configuration
error. Fix the check to accept the former.
Furthermore, this is missing another case where an already selected
device might have a supported devices list that doesn't have the
candidate device. Make this function also check against that, and also
make it accept devices already in the set.
Link: 5245117781
Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>