media: vidtv: use vfree() for memory allocated with vzalloc()

It is allocated with vzalloc(), the corresponding release function
should not be kfree(), use vfree() instead.

Generated by: scripts/coccinelle/api/kfree_mismatch.cocci

Signed-off-by: Yihao Han <hanyihao@vivo.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>