drm/bridge: Call drm_connector_cleanup directly

Remove the unnecessary wrapper functions around drm_connector_cleanup().

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161004222331.7200-1-marex@denx.de