linux-phytec-ti

drm/tegra: dsi: Implement runtime PM

Use runtime PM to clock-(un)gate, (de)assert reset and control power to
the DSI 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>