x86: Use white on black for the console on chromebooks

This is a little easier on the eyes, particularly when the backlight is set
to maximum.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

include/configs/x86-chromebook.h

@@ -51,6 +51,8 @@
 #define CONFIG_ENV_IS_IN_SPI_FLASH
 #define CONFIG_ENV_OFFSET		0x003f8000
 
+#define CONFIG_SYS_WHITE_ON_BLACK
+
 #define CONFIG_STD_DEVICES_SETTINGS     "stdin=usbkbd,i8042-kbd,serial\0" \
 					"stdout=vga,serial\0" \
 					"stderr=vga,serial\0"