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/PM854.h b/include/configs/PM854.h
index 41e290d..3f943aa 100644
--- a/include/configs/PM854.h
+++ b/include/configs/PM854.h
@@ -331,7 +331,7 @@
 #endif
 
 #if defined(CONFIG_SYS_RAMBOOT)
-    #undef CONFIG_CMD_ENV
+    #undef CONFIG_CMD_SAVEENV
     #undef CONFIG_CMD_LOADS
 #endif