[media] ov2640: avoid calling ov2640_select_win() twice

Simplify ov2640_set_params and ov2640_set_fmt.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>