The vc5 HDMI registers hadn't been added into the debugfs
register sets, therefore weren't dumped on request.
Add them in.

Fixes: 83239891 ("drm/vc4: hdmi: Support the BCM2711 HDMI controllers")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://lore.kernel.org/r/20220613144800.326124-19-maxime@cerno.techSigned-off-by: Maxime Ripard <maxime@cerno.tech>