drm/vc4: hdmi: Move HDMI reset to pm_resume

drm/vc4: hdmi: Move HDMI reset to pm_resume

The BCM2835-37 found in the RaspberryPi 0 to 3 have a power domain
attached to the HDMI block, handled in Linux through runtime_pm.

That power domain is shared with the VEC block, so even if we put our
runtime_pm reference in the HDMI driver it would keep being on. If the
VEC is disabled though, the power domain would be disabled and we would
lose any initialization done in our bind implementation.

That initialization involves calling the reset function and initializing
the CEC registers.

Let's move the initialization to our runtime_resume implementation so
that we initialize everything properly if we ever need to.

Fixes: eb2a72c8ef4c ("drm/vc4: hdmi: Move the HSM clock enable to runtime_pm")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://lore.kernel.org/r/20220613144800.326124-24-maxime@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>