drm/bridge: tc358764: add drm_panel_bridge support

Prepare the tc358764 bridge driver for use in a chained setup by
replacing direct use of drm_panel with drm_panel_bridge support.

The bridge panel will use the connector type reported by the panel,
where the connector for this driver hardcodes DRM_MODE_CONNECTOR_LVDS.

The tc358764 did not add any additional info the the connector so the
connector creation is passed to the bridge panel driver.

v3:
  - Merge with patch to make connector creation optional to avoid
    creating two connectors (Laurent)
  - Pass connector creation to bridge panel, as this bridge driver
    did not add any extra info to the connector.
  - Set bridge.type to DRM_MODE_CONNECTOR_LVDS.

v2:
  - Use PTR_ERR_OR_ZERO() (kbuild test robot)

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: kbuild test robot <lkp@intel.com>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Jonas Karlman <jonas@kwiboo.se>
Cc: Jernej Skrabec <jernej.skrabec@siol.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200726203324.3722593-5-sam@ravnborg.org