linux-phytec-ti

drm/tegra: hdmi: Implement runtime PM

Use runtime PM to clock-(un)gate and (de)assert reset to the HDMI
controller. This ties in nicely with atomic DPMS in that a runtime PM
reference is taken before a pipe is enabled and dropped after it has
been shut down.

Signed-off-by: Thierry Reding <treding@nvidia.com>