x86: Add a common include for environment settings

Create a text-file version of x86-common.h which can be used by x86
boards.

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>

include/env/x86.env

@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ * (C) Copyright 2008
+ * Graeme Russ, graeme.russ@gmail.com
+ */
+
+pciconfighost=1
+netdev=eth0
+consoledev=ttyS0
+scriptaddr=0x7000000
+kernel_addr_r=0x1000000
+ramdisk_addr_r=0x4000000
+ramdiskfile=initramfs.gz
+
+/* common console settings */
+stdin=serial,i8042-kbd,usbkbd
+stdout=serial,vidconsole
+stderr=serial,vidconsole