x86: chromebook_link: Enable the syscon uclass

We will use a system controller to model the Intel Management Engine. Enable
this for link.

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

configs/chromebook_link_defconfig

@@ -20,6 +20,8 @@ CONFIG_CMD_BOOTSTAGE=y
 CONFIG_CMD_TPM=y
 CONFIG_CMD_TPM_TEST=y
 CONFIG_OF_CONTROL=y
+CONFIG_REGMAP=y
+CONFIG_SYSCON=y
 CONFIG_CPU=y
 CONFIG_SYS_I2C_INTEL=y
 CONFIG_CMD_CROS_EC=y