nouveau/dmem: fix copy-paste error in nouveau_dmem_migrate_chunk()

Fix call to nouveau_fence_emit() with wrong channel parameter.

Fixes: 7f2a0b50 ("drm/nouveau: fence: separate fence alloc and emit")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230807163238.2091-2-dakr@redhat.com

drivers/gpu/drm/nouveau/nouveau_dmem.c

@@ -678,7 +678,7 @@ static void nouveau_dmem_migrate_chunk(struct nouveau_drm *drm,
 	}
 
 	if (!nouveau_fence_new(&fence))
-		nouveau_fence_emit(fence, chunk->drm->dmem->migrate.chan);
+		nouveau_fence_emit(fence, drm->dmem->migrate.chan);
 	migrate_vma_pages(args);
 	nouveau_dmem_fence_done(&fence);
 	nouveau_pfns_map(svmm, args->vma->vm_mm, args->start, pfns, i);