drm/amdkfd: Fix kernel queue rollback_packet

kq->queue->properties.write_ptr is a GPU address which can'd be
derefenced in the kernel. Use kq->wptr_kernel instead, which is the
kernel CPU address of the same buffer.
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

drivers/gpu/drm/amd/amdkfd/kfd_kernel_queue.c

@@ -279,7 +279,7 @@ static void submit_packet(struct kernel_queue *kq)
 
 static void rollback_packet(struct kernel_queue *kq)
 {
-	kq->pending_wptr = *kq->queue->properties.write_ptr;
+	kq->pending_wptr = *kq->wptr_kernel;
 }
 
 struct kernel_queue *kernel_queue_init(struct kfd_dev *dev,