vmxnet3: add support for ESP IPv6 RSS

Vmxnet3 version 4 added support for ESP RSS. However, only IPv4 was
supported. With vmxnet3 version 6, this patch enables RSS for ESP
IPv6 packets as well.

Signed-off-by: Ronak Doshi <doshir@vmware.com>
Acked-by: Guolin Yang <gyang@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>