drm/nouveau: Spin for a bit in nouveau_fence_wait() before yielding the CPU.

Sleeping doesn't pay off for very short delays in comparison with the
minimum granularity of schedule_timeout().

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
1 file changed