MINOR: h2/stream_interface: Reintroduce te wake() method.

For the time being, reintroduce the wake methods, it may be revisited later.h

src/stream_interface.c

@@ -83,6 +83,7 @@ struct si_ops si_applet_ops = {
 };
 
 struct data_cb si_conn_cb = {
+	.wake    = si_cs_process,
 	.name    = "STRM",
 };