drm/nv50/gr: fix overlap while zeroing zcull regions
drm/nv50/gr: fix overlap while zeroing zcull regions

The specified stride was not correct, resulting in erases overlapping
and part of the zcull regions being not erased at all.

Signed-off-by: Pierre Moreau <06a7711300be5898d6035f8dba5340780a12789c@free.fr>
Signed-off-by: Ben Skeggs <d9f27fb07c1e9f131223ad827fa5179f3846c30b@redhat.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs