radioInterface: Convert diversity argument to general type

Rather than a simple bool type, convert the diversity switch
to the device interface specifer:

  enum InterfaceType {
    NORMAL,
    RESAMP_64M,
    RESAMP_100M,
    DIVERSITY,
  };

The more general specifier allows passing in special cases
other then selection diversity such as multi-ARFCN support.

Signed-off-by: Tom Tsou <tom.tsou@ettus.com>
3 files changed