libcamera: ipu3: Make sure the config is valid

Inspect the return status of validate() in the IPU3 pipeline handler
generateConfigurtion() implementation. If the generated configuration is
not valid, return a an empty configuration to the application.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/pipeline/ipu3/ipu3.cpp

@@ -363,7 +363,8 @@ CameraConfiguration *PipelineHandlerIPU3::generateConfiguration(Camera *camera,
 		config->addConfiguration(cfg);
 	}
 
-	config->validate();
+	if (config->validate() == CameraConfiguration::Invalid)
+		return {};
 
 	return config;
 }