pipe-loader: add a dup() in pipe_loader_sw_probe_kms

pipe-loader: add a dup() in pipe_loader_sw_probe_kms

The pipe_loader_release API closes the fd given, even if the pipe-loader
should _not_ take ownership of it.

With earlier commit we fixed pipe_loader_drm_probe_fd, and now with
cover the final piece.

Note that unlike the DRM case, here the caller _did_ forget to dup
before using it ... most likely leading to all sorts of fun.

Don't forget the close in the error path. Seems like the things are a
bit leaky/asymmetrical with the semi-recent config work. But we can shave
that yak another day ;-)

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>