[media] ivtv: Internally separate encoder & decoder standard setting

Internally separates the setting of the broadcast standard for the encoder &
decoder. Externally there's no change in functionality.

[awalls@md.metrocast.net: Edited to fix a checkpatch gripe about multiple
assignment and to remove a now unused DEFINE_WAIT() due to this patch]

Signed-off-by: Ian Armstrong <ian@iarmst.demon.co.uk>
Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>