arm: kirkwood: ib62x0: build u-boot.kwb

Avoid double typing in the shell and build u-boot.kwb when running "make" only.

Signed-off-by: Luka Perkov <luka.perkov@sartura.hr>
diff --git a/include/configs/ib62x0.h b/include/configs/ib62x0.h
index 9f1dc8a..73caaca 100644
--- a/include/configs/ib62x0.h
+++ b/include/configs/ib62x0.h
@@ -22,6 +22,9 @@
 #define CONFIG_KW88F6281		/* SOC Name */
 #define CONFIG_SKIP_LOWLEVEL_INIT	/* disable board lowlevel_init */
 
+/* Add target to build it automatically upon "make" */
+#define CONFIG_BUILD_TARGET     "u-boot.kwb"
+
 /*
  * Enable device tree support
  */