mb/google/octopus: Add keyboard backlight support

Dorp device support keyboard backlight, so enable it.

BUG=b:138413969
BRANCH=octopus
TEST=emerge-octopus coreboot

Change-Id: If0c7b22b4be2a5d5216404a6944ac887883e9a47
Signed-off-by: Wisley Chen <wisley.chen@quantatw.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34583
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Justin TerAvest <teravest@chromium.org>
Reviewed-by: Marco Chen <marcochen@google.com>

src/mainboard/google/octopus/variants/meep/include/variant/ec.h

@@ -18,4 +18,7 @@
 
 #include <baseboard/ec.h>
 
+/* Enable EC backed Keyboard Backlight in ACPI */
+#define EC_ENABLE_KEYBOARD_BACKLIGHT
+
 #endif