[media] it913x: refactor code largely

Refactor code largely.

Try to keep order of register read/write same as windows driver does as
it makes comparing sniffs easier.

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

diff --cc drivers/media/tuners/it913x.c
Simple merge