[media] it913x: multiple devices on system. Copy ite_config to priv area

If there are two or more different it913x devices on the system they share the same
ite_config and over write its settings.

To over come this, the ite_config is copied to the priv area.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>