net/mlx5: add E-switch VXLAN rule cleanup routines

net/mlx5: add E-switch VXLAN rule cleanup routines

The last part of patchset contains the rule cleanup routines.
These ones is the part of outer interface initialization at
the moment of VXLAN VTEP attaching. These routines query
the list of attached VXLAN devices, the list of local IP
addresses with peer and link scope attribute and the list
of permanent neigh rules, then all found abovementioned
items on the specified outer device are flushed.

Suggested-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
Acked-by: Yongseok Koh <yskoh@mellanox.com>