media: vimc: Remove unused but set variables

Remove unused but set variables to clean up the code and avoid
warning.

Signed-off-by: Lucas A. M. Magalhães <lucmaga@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>