Blackfin: bf506f-ezkit: disable import/export env commands

Space is very tight on this board, so remove more extraneous commands.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/include/configs/bf506f-ezkit.h b/include/configs/bf506f-ezkit.h
index 3580ec6..77b6735 100644
--- a/include/configs/bf506f-ezkit.h
+++ b/include/configs/bf506f-ezkit.h
@@ -82,6 +82,8 @@
  */
 #define CONFIG_ENV_IS_NOWHERE
 #define CONFIG_ENV_SIZE 0x400
+#undef CONFIG_CMD_EXPORTENV
+#undef CONFIG_CMD_IMPORTENV
 
 
 /*