[media] it913x-fe changes to power up and down of tuner

Currently the tuner is constantly powered causing these effects.
1. Remembering last tune channel causing corruptions of changing channel.
2. Causing corruption on other frontend.
3. Higher current in standby of demodulator with clock running.

Power sequence now follows;
Power Up
Tuner on -> Frontend suspend off -> Tuner clk on
Power Down
Frontend suspend on -> Tuner clk off -> Tuner off

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>