event: Support a simple spy record

The current event spy is always passed the event context and the event.
The context is always NULL for a static spy. The event is not often used.

Introduce a 'simple' spy which takes no arguments. This allows us to drop
the adaptation code that many of these spy records use.

Update the event script to find these in the image.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/event.c b/common/event.c
index 3224e28..7e2590e 100644
--- a/common/event.c
+++ b/common/event.c
@@ -71,7 +71,14 @@
 
 			log_debug("Sending event %x/%s to spy '%s'\n", ev->type,
 				  event_type_name(ev->type), event_spy_id(spy));
-			ret = spy->func(NULL, ev);
+			if (spy->flags & EVSPYF_SIMPLE) {
+				const struct evspy_info_simple *simple;
+
+				simple = (struct evspy_info_simple *)spy;
+				ret = simple->func();
+			} else {
+				ret = spy->func(NULL, ev);
+			}
 
 			/*
 			 * TODO: Handle various return codes to