mediawidget: allow better control of deinterlacing mode
Instead of just on/off, allow setting the de-interlacing mode
to the types supported by libVLC.
Also changes default to not do deinterlacing, as most TV programs
nowadays are in progressive mode, and doing de-interlacing on
4K programs can be a very CPU intensive task.
BUG: 389783
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>