event: Add an event for main_loop

Add an event type EVT_MAIN_LOOP that can be used for registering
events that need to be run after the platform has been initialised and
before the main_loop function is called.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Etienne Carriere <etienne.carriere@linaro.org>

common/board_r.c

@@ -579,6 +579,9 @@ static int run_main_loop(void)
 #ifdef CONFIG_SANDBOX
 	sandbox_main_loop_init();
 #endif
+
+	event_notify_null(EVT_MAIN_LOOP);
+
 	/* main_loop() can return to retry autoboot, if so just run it again */
 	for (;;)
 		main_loop();