turnip: Free event->bo on vkDestroyEvent

Fixes a leak from freeing event but not event->bo.

Reviewed-by: Jonathan Marek <jonathan@marek.ca>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3639>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3639>

src/freedreno/vulkan/tu_device.c

@@ -1761,6 +1761,8 @@ tu_DestroyEvent(VkDevice _device,
 
    if (!event)
       return;
+
+   tu_bo_finish(device, &event->bo);
    vk_free2(&device->alloc, pAllocator, event);
 }