kc1: Select libfdt to allow running devicetree-based kernels

Selecting CONFIG_OF_LIBFDT allows running recent mainline kernels.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
diff --git a/configs/kc1_defconfig b/configs/kc1_defconfig
index 4cbe375..06698b8 100644
--- a/configs/kc1_defconfig
+++ b/configs/kc1_defconfig
@@ -13,3 +13,4 @@
 CONFIG_USB=y
 CONFIG_USB_MUSB_GADGET=y
 CONFIG_USB_GADGET=y
+CONFIG_OF_LIBFDT=y