Start the deprecation process for generic board

We should move forward to remove the old board init code. Add a
prominent message to encourage maintainers to get started on this
work.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/main.c b/common/main.c
index 8b6f274..e54f63b 100644
--- a/common/main.c
+++ b/common/main.c
@@ -427,6 +427,12 @@
 
 	bootstage_mark_name(BOOTSTAGE_ID_MAIN_LOOP, "main_loop");
 
+#ifndef CONFIG_SYS_GENERIC_BOARD
+	puts("Warning: Your board does not use generic board. Please read\n");
+	puts("doc/README.generic-board and take action. Boards not\n");
+	puts("upgraded by the late 2014 may break or be removed.\n");
+#endif
+
 #ifdef CONFIG_MODEM_SUPPORT
 	debug("DEBUG: main_loop:   do_mdm_init=%d\n", do_mdm_init);
 	if (do_mdm_init) {