mb/clevo/l140cu: enable S0ix

Enable S0ix for the board, as done in vendor fw.

Change-Id: Ifdf93e1e599e7cc03fc02297eafb49d34b1f6172
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68792
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/clevo/cml-u/variants/l140cu/devicetree.cb

@@ -1,4 +1,5 @@
 chip soc/intel/cannonlake
+	register "s0ix_enable" = "1"
 	register "common_soc_config" = "{
 		/* Touchpad */
 		.i2c[0] = {