rename CONFIG_CMD_ENV to CONFIG_CMD_SAVEENV

The CONFIG_CMD_ENV option controls enablement of the `saveenv` command
rather than a generic "env" command, or anything else related to the
environment.  So, let's make sure the define is named accordingly.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/include/configs/smdk6400.h b/include/configs/smdk6400.h
index c61667f..06d6a88 100644
--- a/include/configs/smdk6400.h
+++ b/include/configs/smdk6400.h
@@ -104,7 +104,7 @@
 #define CONFIG_CMD_REGINFO
 #define CONFIG_CMD_LOADS
 #define CONFIG_CMD_LOADB
-#define CONFIG_CMD_ENV
+#define CONFIG_CMD_SAVEENV
 #define CONFIG_CMD_NAND
 #if defined(CONFIG_BOOT_ONENAND)
 #define CONFIG_CMD_ONENAND