V4L/DVB (8795): saa7134-empress: insert leading null bytes for Beholder M6 empress cards

Additional code to improve the init sequence and add board type tests
were done by Hans Verkuil.

Signed-off-by: Beholder Intl. Ltd. Dmitry Belimov <d.belimov@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>