mb/clevo/cml-u: Use include folder for header files

Change-Id: I50be3d9b829f624cbe460060c40482047f39774c
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47833
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>

src/mainboard/clevo/cml-u/Makefile.inc

@@ -1,2 +1,4 @@
+CPPFLAGS_common += -I$(src)/mainboard/$(MAINBOARDDIR)/variants/$(VARIANT_DIR)/include
+
 ramstage-y += variants/$(VARIANT_DIR)/hda_verb.c
 subdirs-y += variants/$(VARIANT_DIR)

src/mainboard/clevo/cml-u/variants/l140cu/bootblock.c

@@ -2,7 +2,7 @@
 
 #include <bootblock_common.h>
 #include <gpio.h>
-#include "gpio.h"
+#include <variant/gpio.h>
 
 void bootblock_mainboard_init(void)
 {

src/mainboard/clevo/cml-u/variants/l140cu/ramstage.c

@@ -1,7 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
 #include <soc/ramstage.h>
-#include "gpio.h"
+#include <variant/gpio.h>
 
 void mainboard_silicon_init_params(FSP_S_CONFIG *params)
 {