drm/omap: Use the drm_panel_bridge API

drm/omap: Use the drm_panel_bridge API

Replace the manual panel handling code by a drm_panel_bridge. This
simplifies the driver and allows all components in the display pipeline
to be treated as bridges, paving the way to generic connector handling.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.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/20200226112514.12455-25-laurent.pinchart@ideasonboard.com