drm/i915/vma: constify unbind_fence_ops

unbind_fence_ops can be const and placed in rodata.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230818112758.3586545-1-jani.nikula@intel.com

drivers/gpu/drm/i915/i915_vma_resource.c

@@ -94,7 +94,7 @@ static void unbind_fence_release(struct dma_fence *fence)
 	call_rcu(&fence->rcu, unbind_fence_free_rcu);
 }
 
-static struct dma_fence_ops unbind_fence_ops = {
+static const struct dma_fence_ops unbind_fence_ops = {
 	.get_driver_name = get_driver_name,
 	.get_timeline_name = get_timeline_name,
 	.release = unbind_fence_release,