drm/omapdrm: use drm_bridge_chain_get_last_bridge()

Use drm_bridge_chain_get_last_bridge() instead of open coding a loop with
two invocations of drm_bridge_get_next_bridge() per iteration.

Besides being cleaner and more efficient, this change is necessary in
preparation for drm_bridge_get_next_bridge() to get a reference to the
returned bridge.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250801-drm-bridge-alloc-getput-drm_bridge_get_next_bridge-v2-4-888912b0be13@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

Author: lucaceresoli

drivers/gpu/drm/omapdrm/omap_drv.c

@@ -378,10 +378,8 @@ static int omap_display_id(struct omap_dss_device *output)
 	struct device_node *node = NULL;
 
 	if (output->bridge) {
-		struct drm_bridge *bridge = output->bridge;
-
-		while (drm_bridge_get_next_bridge(bridge))
-			bridge = drm_bridge_get_next_bridge(bridge);
+		struct drm_bridge *bridge __free(drm_bridge_put) =
+			drm_bridge_chain_get_last_bridge(output->bridge->encoder);
 
 		node = bridge->of_node;
 	}