net/mlx5e: IPoIB, Enable loopback packets for IPoIB interfaces

Enable loopback of unicast and multicast traffic for IPoIB enhanced
mode.
This will allow interfaces with the same pkey to communicate between
them e.g cloned interfaces that located in different namespaces.

Signed-off-by: Erez Shitrit <erezsh@mellanox.com>
Reviewed-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>