drm: bridge: adv7511: Make connector creation optional

drm: bridge: adv7511: Make connector creation optional

Now that the driver supports all the connector-related bridge
operations, make the connector creation optional. This enables usage of
the adv7511 with the DRM bridge connector helper.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200526011505.31884-5-laurent.pinchart+renesas@ideasonboard.com