drm/omap: Query timing information from analog TV encoder

drm/omap: Query timing information from analog TV encoder

Timings for the TV output are currently reported by the analog TV
connector. This has the disadvantage of having to handle timing-related
operations in a connector omap_dss_device that has, at the hardware
level, no knowledge of any timing information.

Implement the .get_timings() operation in the venc driver, and get
timings from the first component in the pipeline that implements the
operatation. This switches the duty of reporting analog TV timings from
the connector to the encoder.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>