drm/vc4: hvs: Support BCM2712 HVS

The HVS found in the BCM2712, while having a similar role, is very
different from the one found in the previous SoCs. Indeed, the register
layout is fairly different, and the DLIST format is new as well.

Let's introduce the needed functions to support the new HVS.

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