drm/vc4: crtc: Make sure the HDMI controller is powered when disabling

Since commit 875a4d53 ("drm/vc4: drv: Disable the CRTC at boot
time"), during the initial setup of the driver we call into the VC4 HDMI
controller hooks to make sure the controller is properly disabled.

However, we were never making sure that the device was properly powered
while doing so. This never resulted in any (reported) issue in practice,
but since the introduction of commit 4209f03fcb8e ("drm/vc4: hdmi: Warn
if we access the controller while disabled") we get a loud complaint
when we do that kind of access.

Let's make sure we have the HDMI controller properly powered while
disabling it.

Fixes: 875a4d53 ("drm/vc4: drv: Disable the CRTC at boot time")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Nicolas Saenz Julienne <nsaenz@kernel.org>
Tested-by: Nicolas Saenz Julienne <nsaenz@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210923185013.826679-1-maxime@cerno.tech