Replace "run load; run update" with conditionalized "run load update".

The latter version stops when "run load" fails for whatever reasons
rendering the combination *a lot* more secure.

Signed-off-by: Detlev Zundel <dzu@denx.de>
diff --git a/include/configs/walnut.h b/include/configs/walnut.h
index b83660c..f6e99ac 100644
--- a/include/configs/walnut.h
+++ b/include/configs/walnut.h
@@ -73,7 +73,7 @@
 	"update=protect off fffc0000 ffffffff;era fffc0000 ffffffff;"	\
 		"cp.b 100000 fffc0000 40000;"				\
 		"setenv filesize;saveenv\0"				\
-	"upd=run load;run update\0"					\
+	"upd=run load update\0"						\
 	""
 #define CONFIG_BOOTCOMMAND	"run net_nfs"