* Remove unnecessary upcasting. We are now dealing with C++ class objects
and don't need explicit C-style casting in C++ world
* Use helper macro IID_PPV_ARGS() everywhere. It will make code
a little short.
* Use ComPtr smart pointer instead of calling manual IUnknown::Release()
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/2461>