[media] radio-sf16fmr2: convert to generic TEA575x interface
Convert radio-sf16fmr2 to use generic TEA575x implementation. Most of the
driver code goes away as SF16-FMR2 is basically just a TEA5757 tuner
connected to ISA bus.
The card can optionally be equipped with PT2254A volume control (equivalent
of TC9154AP) - the volume setting is completely reworked (with balance control
added) and tested.