mb/google/volteer: Enable keyboard backlight feature

This enables the keyboard backlight feature in ACPI for volteer.

BUG=b:156326050
TEST=Verified 'KBLT' shows up in the DSDT ACPI table.

Change-Id: Id1b1bb059368b0cc36cb06e6cdb8b989060a1dde
Signed-off-by: Caveh Jalali <caveh@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41281
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
diff --git a/src/mainboard/google/volteer/variants/baseboard/include/baseboard/ec.h b/src/mainboard/google/volteer/variants/baseboard/include/baseboard/ec.h
index 981bfae..2d04380 100644
--- a/src/mainboard/google/volteer/variants/baseboard/include/baseboard/ec.h
+++ b/src/mainboard/google/volteer/variants/baseboard/include/baseboard/ec.h
@@ -73,4 +73,7 @@
 /* Enable EC backed PD MCU device in ACPI */
 #define EC_ENABLE_PD_MCU_DEVICE
 
+/* Enable EC backed Keyboard Backlight in ACPI */
+#define EC_ENABLE_KEYBOARD_BACKLIGHT
+
 #endif /* __MAINBOARD_EC_H__ */