libcamera: buffer: Drop friend statement

The Buffer class do not need to friend PipelineHandler, drop it.

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

include/libcamera/buffer.h

@@ -88,7 +88,6 @@ public:
 
 private:
 	friend class Camera;
-	friend class PipelineHandler;
 	friend class Request;
 	friend class Stream;
 	friend class V4L2VideoDevice;