mmal/vout: Support native interlaced modes

mmal/vout: Support native interlaced modes

Add a new flag, which can be used to let mmal select ahdmi mode which matches
the video size and interlacing type. Using this with a proper screen one can
playback for example 1080i content using the screens deinterlacing filters.
The videocore is configured to scan out picture on odd/even field only
according to the top_field_first mode of the video in case of interlaced
video. For progressive video a progressive mode is selected.

Signed-off-by: Julian Scheel <julian@jusst.de>
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>