Add a dependency for UTF8 for LE Audio. Since (nearly?) all
string in LE Audio are UTF8 and that the stack wants to be
able to check and validate strings coming both from remove
deviecs and from the application, it will depend on the utf8
API that is guarded by CONFIG_UTF8.
Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>
d74f5d7d23