[media] it913x: re-implement sleep

Re-implement sleep. Based USB sniffs taken from the latest Hauppauge
windows driver version 07/10/2014, 14.6.23.32191.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>