warp: Fix the 'saveenv' command

After the mx6 config consolidation, 'save' command is no longer
recognized.

Pass the full command name 'saveenv' instead.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/board/warp/README b/board/warp/README
index db3100e..22f9055 100644
--- a/board/warp/README
+++ b/board/warp/README
@@ -34,7 +34,7 @@
 Use the default environment variables:
 
 => env default -f -a
-=> save
+=> saveenv
 
 Run the DFU command:
 => dfu 0 mmc 0