drm/vc4: hdmi: Add MISC_CONTROL register for vc4

The MISC_CONTROL register allows configuration of pixel repetition
for pixel doubling in the HDMI block instead of PixelValve.
It was already defined for vc5, so add it for vc4.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://lore.kernel.org/r/20220613144800.326124-29-maxime@cerno.tech


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