media: em28xx: Add support for MyGica UTV3

The MyGica UTV3 Analog USB2.0 TV Box is a USB video capture card
that has analog TV, composite video, and FM radio inputs, an IR
remote, and provides audio only as Line Out, but not over USB.
Mine is prepared for an FM tuner, but not equipped with one.
Support for FM radio is therefore missing. The device contains:
 - Empia EM2860 USB bridge
 - Philips SAA7113 video decoder
 - NXP TDA9801T demodulator
 - Tena TNF931D-DFDR1 tuner
 - ST HCF4052 demux, switches input audio to Line Out

Signed-off-by: Nils Rothaug <nils.rothaug@gmx.de>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>