event: Convert existing spy records to simple

Very few of the existing event-spy records use the arguments they are
passed. Update them to use a simple spy instead, to simplify the code.

Where an adaptor function is currently used, remove it where possible.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/fwu_updates/fwu.c b/lib/fwu_updates/fwu.c
index 22bdc78..b580574 100644
--- a/lib/fwu_updates/fwu.c
+++ b/lib/fwu_updates/fwu.c
@@ -618,7 +618,7 @@
 	return ret;
 }
 
-static int fwu_boottime_checks(void *ctx, struct event *event)
+static int fwu_boottime_checks(void)
 {
 	int ret;
 	u32 boot_idx, active_idx;
@@ -682,4 +682,4 @@
 
 	return 0;
 }
-EVENT_SPY(EVT_MAIN_LOOP, fwu_boottime_checks);
+EVENT_SPY_SIMPLE(EVT_MAIN_LOOP, fwu_boottime_checks);