efi_loader: Put back copyright message

This was lost in a later commit, so add it back.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

lib/efi_loader/helloworld.c

@@ -2,6 +2,9 @@
 /*
  * Hello world EFI application
  *
+ * Copyright (c) 2016 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
  * Copyright 2020, Heinrich Schuchardt <xypron.glpk@gmx.de>
  *
  * This test program is used to test the invocation of an EFI application.