drm/nouveau/kms/nv50-gp1xx: add WAR for EVO push buffer HW bug

Thanks to NVIDIA for confirming this workaround, and clarifying which HW
is affected.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Tested-by: Alexander Kapshuk <alexander.kapshuk@gmail.com>
1 file changed