drm/display: bridge-connector: attach the encoder to the created connector

drm/display: bridge-connector: attach the encoder to the created connector

Currently all users of the bridge-connector must call
drm_connector_attach_encoder() immediately after a successful
drm_bridge_connector_init().

This is an unnecessary burden for users. Move the call to the end of
drm_bridge_connector_init() so all callers can be simplified.

Update documentation accordingly, rewording a bit the whole paragraph which
would otherwise become poorly readable due to the growing list of actions.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://patch.msgid.link/20260423-drm-bridge-connector-attach_encoder-v2-1-2ae6ca69b390@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>