V4L/DVB (3810): KWorld HardwareMpegTV XPert: Enable Blackbird MPEG encoder support

- clear I2SIN to deliver the audio stream to the cx23416 mpeg encoder.
- enable blackbird support on the KWorld HardwareMpegTV XPert

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>