[media] tvp514x: Fix double free

The tvp514x data structure is allocated using devm_kzalloc(). Freeing it
explictly would result in a double free. Fix it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>