frontend/stream/LiteEthStream2UDPTX: Fix/Simplify no FIFO case.

liteeth/frontend/stream.py

@@ -20,11 +20,12 @@ class LiteEthStream2UDPTX(Module):
         if fifo_depth is None:
             assert send_level == 1
             self.comb += [
-                source.valid.eq(sink.valid),
+                sink.connect(source, keep={"valid", "ready", "data"}),
                 source.last.eq(1),
-                source.length.eq(1),
-                source.data.eq(sink.data),
-                sink.ready.eq(source.ready)
+                source.src_port.eq(udp_port),
+                source.dst_port.eq(udp_port),
+                source.ip_address.eq(ip_address),
+                source.length.eq(1)
             ]
         else:
             level   = Signal(max=fifo_depth+1)