mb/google/brya/var/dochi: Enable EC keyboard backlight

Enable EC keyboard backlight for dochi.

BUG=b:299284564
TEST=FW_NAME=dochi emerge-brya coreboot chromeos-bootimage

Change-Id: I1b640c576fcdd368110b88cba6f969f10dfc15f1
Signed-off-by: Morris Hsu <morris-hsu@quanta.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78395
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Bob Moragues <moragues@google.com>
Reviewed-by: David Wu <david_wu@quanta.corp-partner.google.com>
Reviewed-by: Eric Lai <ericllai@google.com>

src/mainboard/google/brya/variants/dochi/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