event: Convert arch_cpu_init_dm() to use events

Instead of a special function, send an event after driver model is inited
and adjust the boards which use this function.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/event.h b/include/event.h
index 6b347e9..78a4237 100644
--- a/include/event.h
+++ b/include/event.h
@@ -20,6 +20,7 @@
 	EVT_TEST,
 
 	/* Events related to driver model */
+	EVT_DM_POST_INIT,
 	EVT_DM_PRE_PROBE,
 	EVT_DM_POST_PROBE,
 	EVT_DM_PRE_REMOVE,