net/mlx5e: Set uplink rep as NETNS_LOCAL

Previously, NETNS_LOCAL was not set for uplink representors, inconsistent
with VF representors, and allowed the uplink representor to be moved
between net namespaces and separated from the VF representors it shares
the core device with. Such usage would break the isolation model of
namespaces, as devices in different namespaces would have access to
shared memory.

To solve this issue, set NETNS_LOCAL for uplink representors if eswitch is
in switchdev mode.

Fixes: 7a9fb35e ("net/mlx5e: Do not reload ethernet ports when changing eswitch mode")
Signed-off-by: Gavin Li <gavinl@nvidia.com>
Reviewed-by: Gavi Teitz <gavi@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>