net/mlx5e: Move the LRO-XSK check to mlx5e_fix_features

LRO is mutually exclusive with XSK. When LRO is enabled, it checks
whether XSK is active. This commit moves this check to a more correct
place at mlx5e_fix_features.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>