drm/vc4: vec: Support progressive modes

The VEC is able to output progressive analog modes, but the driver has
never set the proper bit to do so.

Signed-off-by: Mateusz Kwiatkowski <kfyatek+publicgit@gmail.com>
Link: https://lore.kernel.org/r/20221207-rpi-hvs-crtc-misc-v1-15-1f8e0770798b@cerno.tech


Signed-off-by: Maxime Ripard <maxime@cerno.tech>