defaultenv: do not print usage information for update script
This usage printout during startup more looks like there is
something wrong with the environment than a helpful message.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Eric Bénard <eric@eukrea.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>