hwupload: assume that hwmap_class->uninit() is always defined
hwupload: assume that hwmap_class->uninit() is always defined

We already require hwmap_class->init() and hwmap_class->map_frame() to
be defined and there is no need to treat hwmap_class->uninit()
differently.

gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl