net/mlx5: introduce encapsulation rules container

net/mlx5: introduce encapsulation rules container

Currently the VXLAN encapsulation neigh/local rules
are stored in the list contained in the VTEP device
structure. Encapsulation VTEP device is attached to
outer interface and stored rules are related to this
underlying interface. We are going to use unattached
VXLAN devices for encapsulation (kernel does not use
attached interface to find egress one), so we should
introduce the structure to keep interface related
neigh/local rules instead of VTEP structure. This
patch introduces internal tcf_irule structure, and
its create/delete methods.

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>