media: visl: make visl_qops static

This struct can be static. This fixes a sparse warning:

visl-video.c:690:22: warning: symbol 'visl_qops' was not declared. Should it be static?

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>