DVB (2420): Makes integration of future devices easier

- To make the integration of future devices easier
- modified the dvb-usb-part to allow a device-specific firmware download
- added an option to specify whether a device reconnects after a firmware download or not.

Signed-off-by: Patrick Boettcher <pb@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>