net/mlx5e: Check tunnel offload is required before setting SWP

Check that tunnel offload is required before setting Software Parser
offsets to get Geneve HW offload. In case of Geneve packet we check HW
offload support of SWP in mlx5e_tunnel_features_check() and set features
accordingly, this should be reflected in skb offload requested by the
kernel and we should add the Software Parser offsets only if requested.
Otherwise, in case HW doesn't support SWP for Geneve, data path will
mistakenly try to offload Geneve SKBs with skb->encapsulation set,
regardless of whether offload was requested or not on this specific SKB.

Fixes: e3cfc7e6 ("net/mlx5e: TX, Add geneve tunnel stateless offload support")
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>