radeonsi: allocate filled_size for streamout targets in set_streamout_buffers

so that create_stream_output_target doesn't use the context and can be
called from any thread. This is for u_threaded_context.

Reviewed-by: Zoltán Böszörményi <zboszor@gmail.com>
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9028>
1 file changed