net/mlx5e: Add NETIF_F_HW_TC to hw_features when HTB offload is available

If a feature flag is only present in features, but not in hw_features,
the user can't reset it. Although hw_features may contain NETIF_F_HW_TC
by the point where the driver checks whether HTB offload is supported,
this flag is controlled by another condition that may not hold. Set it
explicitly to make sure the user can disable it.

Fixes: 214baf22

 ("net/mlx5e: Support HTB offload")
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>