drm/vc4: Relax VEC modeline requirements and add progressive mode support

Make vc4_vec_encoder_atomic_check() accept arbitrary modelines, as long
as they result in somewhat sane output from the VEC. The bounds have
been determined empirically. Additionally, add support for the
progressive 262-line and 312-line modes.

Signed-off-by: Mateusz Kwiatkowski <kfyatek+publicgit@gmail.com>