net/mlx5e: Properly disable vlan strip on non-UL reps

[ Upstream commit f37044fd ]

When querying mlx5 non-uplink representors capabilities with ethtool
rx-vlan-offload is marked as "off [fixed]". However, it is actually always
enabled because mlx5e_params->vlan_strip_disable is 0 by default when
initializing struct mlx5e_params instance. Fix the issue by explicitly
setting the vlan_strip_disable to 'true' for non-uplink representors.

Fixes: cb67b832

 ("net/mlx5e: Introduce SRIOV VF representors")
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>