[media] sur40: set q->dev instead of allocating a context

Stop using alloc_ctx and just fill in the device pointer.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Florian Echtler <floe@butterbrot.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>