drm/vc4: hdmi: Add support for BCM2712 HDMI controllers

The HDMI controllers found in the BCM2712 are largely the ones found in
the BCM2711 with a different PHY.

There's some difference with how timings are split between registers,
and HDMI1 is now able to run at 4k/60Hz.

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