x86: Use CONFIG_CHROMEOS_VBOOT for verified boot

At present CONFIG_CHROMEOS is used to determine whether verified boot is
in use. The code to implement that is not in U-Boot mainline.

However, it is useful to be able to boot a Chromebook in developer mode
in U-Boot mainline without needing the verified boot code.

To allow this, use CONFIG_CHROMEOS_VBOOT to indicate that verified boot
should be used, and CONFIG_CHROMEOS to indicate that the board supports
Chrome OS. That allows us to define CONFIG_CHROMEOS on coral.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/common/Kconfig.boot b/common/Kconfig.boot
index 522f5f3..3f6d9c1 100644
--- a/common/Kconfig.boot
+++ b/common/Kconfig.boot
@@ -343,6 +343,23 @@
 	  used for booting OS with different memory setup where the part of
 	  the memory location should be used for different purpose.
 
+config CHROMEOS
+	bool "Support booting Chrome OS"
+	help
+	  Chrome OS requires U-Boot to set up a table indicating the boot mode
+	  (e.g. Developer mode) and a few other things. Enable this if you are
+	  booting on a Chromebook to avoid getting an error about an invalid
+	  firmware ID.
+
+config CHROMEOS_VBOOT
+	bool "Support Chrome OS verified boot"
+	help
+	  This is intended to enable the full Chrome OS verified boot support
+	  in U-Boot. It is not actually implemented in the U-Boot source code
+	  at present, so this option is always set to 'n'. It allows
+	  distinguishing between booting Chrome OS in a basic way (developer
+	  mode) and a full boot.
+
 endmenu		# Boot images
 
 menu "Boot timing"