V4L/DVB (6715): ivtv: Remove unnecessary register update

To reduce the number of display register accesses, the yuv code keeps track of
the current video settings. Should there be a change in any single parameter,
it will update the associated display registers to ensure everything is
displayed correctly.

The existing check also looks at the field order for the video. This is not
required, since field reversal does not require any display register changes.

This patch removes the field order from the check.

Signed-off-by: Ian Armstrong <ian@iarmst.demon.co.uk>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>