mb/google/trulo/var/kaladin: Enable EC keyboard backlight

Enable EC keyboard backlight for kaladin.

BUG=b:439234109
TEST=emerge-nissa coreboot chromeos-bootimage
     confirm KBLT device appear in DSDT table

Change-Id: I981ca717405a84794390388bf62a97d1c23f33a7
Signed-off-by: wu.garen <wu.garen@inventec.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/88970
Reviewed-by: Eric Lai <ericllai@google.com>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/brya/variants/kaladin/include/variant/ec.h

@@ -5,4 +5,7 @@
 
 #include <baseboard/ec.h>
 
+/* Enable EC backed Keyboard Backlight in ACPI */
+#define EC_ENABLE_KEYBOARD_BACKLIGHT
+
 #endif