libcamera: pipeline_handler: Return unique_ptr from generateConfiguration()

The PipelineHandler::generateConfiguration() function allocates a
CameraConfiguration instance and returns it. The ownership of the
instance is transferred to the caller. This is a perfect match for a
std::unique_ptr<>, which the Camera::generateConfiguration() function
already returns. Update PipelineHandler::generateConfiguration() to
match it. This fixes a memory leak in one of the error return paths in
the IPU3 pipeline handler.

While at it, update the Camera::generateConfiguration() function
documentation to drop the sentence that describes the ownership
transfer, as that is implied by usage of std::unique_ptr<>.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/pipeline/vimc/vimc.cpp

@@ -84,7 +84,7 @@ class PipelineHandlerVimc : public PipelineHandler
 public:
 	PipelineHandlerVimc(CameraManager *manager);
 
-	CameraConfiguration *generateConfiguration(Camera *camera,
+	std::unique_ptr<CameraConfiguration> generateConfiguration(Camera *camera,
 		const StreamRoles &roles) override;
 	int configure(Camera *camera, CameraConfiguration *config) override;
 
@@ -189,11 +189,13 @@ PipelineHandlerVimc::PipelineHandlerVimc(CameraManager *manager)
 {
 }
 
-CameraConfiguration *PipelineHandlerVimc::generateConfiguration(Camera *camera,
+std::unique_ptr<CameraConfiguration>
+PipelineHandlerVimc::generateConfiguration(Camera *camera,
 	const StreamRoles &roles)
 {
 	VimcCameraData *data = cameraData(camera);
-	CameraConfiguration *config = new VimcCameraConfiguration(data);
+	std::unique_ptr<CameraConfiguration> config =
+		std::make_unique<VimcCameraConfiguration>(data);
 
 	if (roles.empty())
 		return config;