The env change its implementation after this log, while env mmc
didn't change it immediately, which cause issue. Follow to the
new style to fix it.

commit ea882baf
Author: Wolfgang Denk <wd@denx.de>
Date:   Sun Jun 20 23:33:59 2010 +0200

    New implementation for internal handling of environment variables.

Signed-off-by: Lei Wen <leiwen@marvell.com>