[media] media: i2c: tvp514x: remove manual setting of subdev name

This patch removes manual setting of subdev name in the
probe, ideally subdev names must be unique.

Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>