radioInterface: Remove UmTRX 'diversity' option

The 'diversity' option was an experimental 2 antenna receiver
implementation for UmTRX. The implementation has not been
maintained and current working status is unknown.

In addition to code rot, Coverity is triggering errors in the
associated code sections.

Removal of code cleans up many cases of special handling that
were necessary to accommodate the implementation.

Change-Id: I46752ccf5dbcffbec806081dec03e69a0fbdcdb7
9 files changed