media: allegro: add a version field to mcu messages

In order to distinguish the message format that is expected by the
firmware, add a version field to the message header. This allows to
encode and decode the messages for the version of the firmware that was
loaded by the driver.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>