MINOR: stream-int/conn-stream: Move si_cs_io_cb() in the conn-stream scope

si_cs_io_cb() is renamed cs_conn_io_cb(). In addition, the context of the
tasklet used to wake-up the conn-stream is now a conn-stream.
diff --git a/src/debug.c b/src/debug.c
index 6f482d2..1e83c11 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -252,8 +252,8 @@
 		s = (struct stream *)task->context;
 	else if (task->process == task_run_applet && task->context)
 		s = cs_strm(((struct appctx *)task->context)->owner);
-	else if (task->process == si_cs_io_cb && task->context)
-		s = cs_strm(((struct stream_interface *)task->context)->cs);
+	else if (task->process == cs_conn_io_cb && task->context)
+		s = cs_strm(((struct conn_stream *)task->context));
 
 	if (s)
 		stream_dump(buf, s, pfx, '\n');