mb/google/dedede: Enable FW_CONFIG

Enable FW_CONFIG and add tablet mode field in devicetree

BUG=b:165613510
TEST=emerge-dedede coreboot

Signed-off-by: Wisley Chen <wisley.chen@quantatw.com>
Change-Id: I55e4c0d0b4aa2337c01773006d0b485fdcd91654
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45185
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>

src/mainboard/google/dedede/Kconfig

@@ -11,6 +11,8 @@ config BOARD_GOOGLE_BASEBOARD_DEDEDE
 	select EC_GOOGLE_CHROMEEC_BOARDID
 	select EC_GOOGLE_CHROMEEC_ESPI
 	select EC_GOOGLE_CHROMEEC_SKUID
+	select FW_CONFIG
+	select FW_CONFIG_SOURCE_CHROMEEC_CBI
 	select GOOGLE_SMBIOS_MAINBOARD_VERSION
 	select HAVE_ACPI_RESUME
 	select HAVE_ACPI_TABLES

src/mainboard/google/dedede/variants/baseboard/devicetree.cb

@@ -1,3 +1,10 @@
+fw_config
+        field TABLETMODE 10
+                option TABLETMODE_DISABLED 0
+                option TABLETMODE_ENABLED 1
+        end
+end
+
 chip soc/intel/jasperlake
 	device cpu_cluster 0 on
 		device lapic 0 on end