x86: efi-x86_app: Convert to text environment

Use the common include. Drop the unnecessary changes, since missing
stdio drivers will be ignored.

Drop everything from the config.h file.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> # Intel Edison
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/board/efi/efi-x86_app/efi-x86_app.env b/board/efi/efi-x86_app/efi-x86_app.env
new file mode 100644
index 0000000..106836a
--- /dev/null
+++ b/board/efi/efi-x86_app/efi-x86_app.env
@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2015 Google, Inc
+ */
+
+#include <env/x86.env>