hv_netvsc: use single existing drop path in netvsc_start_xmit

... which validly uses dev_kfree_skb_any() instead of dev_kfree_skb().

Setting ret to -EFAULT and -ENOMEM have no real meaning here (we need to set
it to anything but -EAGAIN) as we drop the packet and return NETDEV_TX_OK
anyway.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>