tun: There is no longer any need to deny changing network namespaces

With the awkward case between free_netdev and dev_chr_close fixed
there is no longer any need to limit tun and tap devices to the
network namespace they were created in.  So remove the
NETIF_F_NETNS_LOCAL flag on the network device.
Signed-off-by: NEric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/tun.c

@@ -810,7 +810,6 @@ static void tun_setup(struct net_device *dev)
 
 	dev->ethtool_ops = &tun_ethtool_ops;
 	dev->destructor = free_netdev;
-	dev->features |= NETIF_F_NETNS_LOCAL;
 }
 
 static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)