drm/display: bridge_connector: get/put the panel_bridge

The panel_bridge pointer is taken inside the loop and used after the
loop. Being a local variable, use a cleanup action to ensure it is put on
return.

Based on the code structure the panel_bridge pointer might be assigned
during multiple loop iterations. Even though this is probably not possible
in the practice, ensure there is no reference leak by putting the reference
to the old value before overwriting with the new value.

Reviewed-by: Louis Chauvet <[e-mail]>
Reviewed-by: Dmitry Baryshkov <[e-mail]>
Tested-by: Dmitry Baryshkov <[e-mail]> # db410c
Tested-by: Geert Uytterhoeven <[e-mail]>
Tested-by: Nicolas Frattaroli <[e-mail]>
Tested-by: Tommaso Merciai <[e-mail]>
Tested-by: Marek Szyprowski <[e-mail]>
Link: https://patch.msgid.link/20251017-drm-bri[e-mail]
Signed-off-by: Luca Ceresoli <[e-mail]>

drivers/gpu/drm/display/drm_bridge_connector.c

···
 	struct drm_bridge_connector *bridge_connector;
 	struct drm_connector *connector;
 	struct i2c_adapter *ddc = NULL;
-	struct drm_bridge *panel_bridge = NULL;
+	struct drm_bridge *panel_bridge __free(drm_bridge_put) = NULL;
 	unsigned int supported_formats = BIT(HDMI_COLORSPACE_RGB);
 	unsigned int max_bpc = 8;
 	bool support_hdcp = false;
···
 		if (bridge->ddc)
 			ddc = bridge->ddc;
 
-		if (drm_bridge_is_panel(bridge))
-			panel_bridge = bridge;
+		if (drm_bridge_is_panel(bridge)) {
+			drm_bridge_put(panel_bridge);
+			panel_bridge = drm_bridge_get(bridge);
+		}
 
 		if (bridge->support_hdcp)
 			support_hdcp = true;