drm/msm/hdmi: implement proper runtime PM handling

drm/msm/hdmi: implement proper runtime PM handling

It is completely not obvious, but the so-called 'hpd' clocks and
regulators are required for the HDMI host to function properly. Merge
pwr and hpd regulators. Use regulators, clocks and pinctrl to implement
proper runtime PM callbacks.

Reviewed-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/651715/
Link: https://lore.kernel.org/r/20250505-fd-hdmi-hpd-v5-9-48541f76318c@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>