[media] media: i2c: ths7303: remove init_enable option from pdata

This patch removes init_enable option from pdata, the init_enable
was intended that the device should start streaming video immediately
but ideally the bridge drivers should call s_stream explicitly for such
devices to start video.

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