Revert "net/mlx5e: Block offload of outer header csum for UDP tunnels"

Revert "net/mlx5e: Block offload of outer header csum for UDP tunnels"

This reverts commit 00be83c09781501a88f7901ea4488dc046ad5111.

Although the NIC doesn't support offload of outer header CSUM, using
gso_partial_features allows offloading the tunnel's segmentation. The
driver relies on the stack CSUM calculation of the outer header. For
this, NETIF_F_GSO_UDP_TUNNEL_CSUM must be a member of the device's
features.

Fixes: 00be83c09781 ("net/mlx5e: Block offload of outer header csum for UDP tunnels")
Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>