mb/google/dedede/var/drawcia: Enable EC keyboard backlight

BUG=b:168847046
TEST=emerge-dedede coreboot chromeos-bootimage

Signed-off-by: Wisley Chen <wisley.chen@quantatw.com>
Change-Id: I16ed22aa5e270ad2d5c964764cc134b72941d4e4
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45570
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Henry Sun <henrysun@google.com>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>

src/mainboard/google/dedede/variants/drawcia/include/variant/ec.h

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