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/configs/chromebook_coral_defconfig b/configs/chromebook_coral_defconfig
index 0ec95af..827974f 100644
--- a/configs/chromebook_coral_defconfig
+++ b/configs/chromebook_coral_defconfig
@@ -21,6 +21,7 @@
 CONFIG_X86_OFFSET_U_BOOT=0xffd00000
 CONFIG_X86_OFFSET_SPL=0xffe80000
 CONFIG_INTEL_GENERIC_WIFI=y
+CONFIG_CHROMEOS=y
 CONFIG_BOOTSTAGE=y
 CONFIG_SPL_BOOTSTAGE=y
 CONFIG_TPL_BOOTSTAGE=y