arm: kirkwood: ib62x0: drop dev CONFIG_OF_LIBFDT

It is already defined in included mv-common.h file.

Signed-off-by: Luka Perkov <luka.perkov@sartura.hr>
diff --git a/include/configs/ib62x0.h b/include/configs/ib62x0.h
index 976147d..fb59ce2 100644
--- a/include/configs/ib62x0.h
+++ b/include/configs/ib62x0.h
@@ -26,11 +26,6 @@
 #define CONFIG_BUILD_TARGET     "u-boot.kwb"
 
 /*
- * Enable device tree support
- */
-#define CONFIG_OF_LIBFDT
-
-/*
  * Compression configuration
  */
 #define CONFIG_BZIP2