V4L/DVB (5829): Firmware extract and loading for opera dvb-usb update

Better way of creating and loading the firmware used.
Update for get_dvb_firmware script to extract the files for opera usb-box
Help file for creating the firmware added

Signed-off-by: Marco Gittler <g.marco@freenet.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>