Merge branch 'tunnels'

Merge branch 'tunnels'

Nicolas Dichtel says:

====================
tunnels: don't allow to add the same tunnel twice

This series fixes the check of an existing tunnel with the same
parameters when a new tunnel is added.  I've checked all users of
ip_tunnel_newlink(): gre, gretap, ipip and vti. The bug exists only
for gre and vti.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>