drm/tilcdc: Use devm_drm_of_get_bridge() helper

drm/tilcdc: Use devm_drm_of_get_bridge() helper

Replace drm_of_find_panel_or_bridge() with the newer
devm_drm_of_get_bridge() helper which simplifies the code by:
- Automatically handling both panel and bridge cases internally
- Managing the panel-to-bridge conversion when needed
- Using devres for resource management, eliminating manual cleanup

This removes the need for explicit panel-to-bridge conversion via
devm_drm_panel_bridge_add_typed() and the associated error handling path.

Signed-off-by: Kory Maincent (TI.com) <kory.maincent@bootlin.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Link: https://patch.msgid.link/20260123-feature_tilcdc-v5-20-5a44d2aa3f6f@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>