cso: fix stream-out clean up in cso_release_all()

cso: fix stream-out clean up in cso_release_all()

Use the has_streamout flag as we do elsewhere to check if we need
to call pipe->set_stream_output_targets().  The driver might implement
the set_stream_output_targets() function, but not for all hardware
configurations.

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>