x86: Add coreboot timestamps

Add selected coreboot timestamps into bootstage to get a unified view of
the boot timings.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/x86/cpu/coreboot/coreboot.c

@@ -91,6 +91,9 @@ void show_boot_progress(int val)
 
 int last_stage_init(void)
 {
+	if (gd->flags & GD_FLG_COLD_BOOT)
+		timestamp_add_to_bootstage();
+
 	return 0;
 }