WR streamers: State unused in xrx_streamer.vhd
In wr_streamers, the state machine in file xrx_streamer.vhd, in
process p_fsm, specifies the state SUBFRAME_HEADER and even implements
it with some functionality, but this state is never reached.
No other state leads to it.
To be discussed what the state represents, whether it is required or
not.