If i-th thread could not be created it means we have i threads,
not i+1, because we start from 0.
Fixes: 404d0d5 "gallium/u_queue: add an option to have multiple worker threads" Signed-off-by: Grazvydas Ignotas <notasas@gmail.com> Signed-off-by: Marek Olšák <marek.olsak@amd.com>