wined3d: Do not use a staging buffer if discarding a mappable buffer in adapter_vk_copy_bo_address().

As in wined3d_buffer_vk_upload_ranges().
Signed-off-by: Zebediah Figura <z.figura12@gmail.com>
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>