Add a command to sleep for n milliseconds.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Steffen Trumtrar authored on 13 Jun 2012 Sascha Hauer committed on 30 Jun 2012