hv_netvsc: change GPAD teardown order on older versions

On older versions of Windows, the host ignores messages after
vmbus channel is closed.

Workaround this by doing what Windows does and send the teardown
before close on older versions of NVSP protocol.

Reported-by: Mohammed Gamal <mgamal@redhat.com>
Fixes: 0cf73780

 ("hv_netvsc: netvsc_teardown_gpadl() split")
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>