msi3101: add default FMT and ADC frequency

Default ADC to smallest/worst possible configuration on probe.
Also enhance some FMT debug logs.

Signed-off-by: Antti Palosaari <crope@iki.fi>
msi3101: sleep USB ADC and tuner when streaming is stopped

Put USB IF / ADC and RF tuner to sleep when device is not streaming.
It uses around 115 mA power from USB when active, which drops to
32 mA on idle after that patch.

Signed-off-by: Antti Palosaari <crope@iki.fi>