The following modifications are applied to allow RFNoC blocks with zero
input- or output ports (or none at all):
- The backend interface will no longer synthesize any flushing logic if
there are no streaming ports
- The Mako templates are modified to allow generating code for blocks
without streaming ports
- The BFM for RFNoC blocks (RfnocBlockCtrlBfm) is partially factored out
into a parent class (RfnocBlockCtrlBfmCtrlOnly) which allows the
simulation of such RFNoC blocks
Original-commit: 878cfcf48f125826e9d48b7c61a4ee7fd19e9a94
Martin Braun
8af1711952