V4L/DVB (9633): Put s5h1411 into low power mode at end of attach() call

Place the s5h1411 into low power mode until first use (to handle the case where
the user plugs in the device and then doesn't use it for a while).  On the
Pinnacle 801e, this brings the power usage from 126ma down to 82ma.

Signed-off-by: Devin Heitmueller <devin.heitmueller@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>