net/sched: tunnel_key: Allow to set tos and ttl for tc based ip tunnels

Allow user-space to provide tos and ttl to be set for the tunnel headers.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>