V4L/DVB (7248): dabfirmware.h add missing license

Received written ack from the dabusb author
that the firmware is BSD licensed.
As bonus clarify copyright holder.

Signed-off-by: maximilian attems <max@stro.at>
Acked-by: Deti Fliegl <deti@fliegl.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>