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/delta.h b/include/configs/delta.h
index abb2676..8cbeb9a 100644
--- a/include/configs/delta.h
+++ b/include/configs/delta.h
@@ -108,7 +108,7 @@
 
 #else
 
-#define CONFIG_CMD_ENV
+#define CONFIG_CMD_SAVEENV
 #define CONFIG_CMD_NAND
 #define CONFIG_CMD_I2C