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/common/cmd_nvedit.c b/common/cmd_nvedit.c
index 1fcb4c9..02b18ec 100644
--- a/common/cmd_nvedit.c
+++ b/common/cmd_nvedit.c
@@ -546,7 +546,7 @@
 	return (-1);
 }
 
-#if defined(CONFIG_CMD_ENV) && !defined(CONFIG_ENV_IS_NOWHERE)
+#if defined(CONFIG_CMD_SAVEENV) && !defined(CONFIG_ENV_IS_NOWHERE)
 
 int do_saveenv (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 {