[media] omap3isp: Default to progressive field order when setting the format

If the requested field order is not supported default to progressive as
we can't guess how the user will configure the pipeline later on.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Enrico Butera <ebutera@users.sourceforge.net>
Acked-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>