x86: start64: Fix copyright message

There is a typo in this header. Fix it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/cpu/start64.S b/arch/x86/cpu/start64.S
index a78a331..7be8347 100644
--- a/arch/x86/cpu/start64.S
+++ b/arch/x86/cpu/start64.S
@@ -2,7 +2,7 @@
 /*
  * 64-bit x86 Startup Code
  *
- * (C) Copyright 216 Google, Inc
+ * Copyright 2019 Google, Inc
  * Written by Simon Glass <sjg@chromium.org>
  */