CLEANUP: connection: rename the wait_event.task field to .tasklet

It's really confusing to call it a task because it's a tasklet and used
in places where tasks and tasklets are used together. Let's rename it
to tasklet to remove this confusion.
diff --git a/include/types/connection.h b/include/types/connection.h
index 54f8d1a..cc2fb17 100644
--- a/include/types/connection.h
+++ b/include/types/connection.h
@@ -65,7 +65,7 @@
 };
 
 struct wait_event {
-	struct tasklet *task;
+	struct tasklet *tasklet;
 	int events;             /* set of enum sub_event_type above */
 };