drm/omap: Move DISPC runtime PM handling to omapdrm

drm/omap: Move DISPC runtime PM handling to omapdrm

The internal encoders (DSI, HDMI4, HDMI5 and VENC) runtime PM handlers
attempt to manage the runtime PM state of the connected DISPC, based on
the rationale that the DISPC providing data to the encoders requires
ensuring that the display is active whenever the encoders are active.

While the DISPC provides data to the encoders, it doesn't as such
constitute a resource that encoders require in order to be taken out
of suspend, contrary to for instance a functional clock or a power
supply. Encoders registers can be accessed without the DISPC being
active, and while the encoders will not output any video stream without
being fed by the DISPC, the DISPC PM state doesn't influence the
encoders PM state.

For this reason the DISPC PM state is better managed from the omapdrm
driver, in the CRTC enable and disable operations. This allows the
encoders PM state to be handled separately from the DISPC, and in
particular at times when the DISPC may not be available (for instance at
probe due to the DSS probe being deferred, or at remove time du to the
DISPC being already removed).

Fixes: edb715dffdee ("drm/omap: dss: dsi: Move initialization code from bind to probe")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181110111654.4387-5-laurent.pinchart@ideasonboard.com