add firmware for Si2168 demod and Si2158 tuner

These firmwares are needed for PCTV 292e (support in 3.16 using firmware dvb-demod-si2168-02.fw and from 3.17 ahead with firmware dvb-demod-si2168-b40-01.fw) and TechnoTrend CT2-4400 (support in 3.17 likely, uses firmwares dvb-demod-si2168-a30-01.fw and dvb-tuner-si2158-a20-01.fw).

I'm submitting a patch for OE using 3.14/3.15 kernel to enable support of these devices.