Driver doesn't support aRFS for encapsulated packets, return early error
in such a case.
Fixes: 1e39d780db50 ("net/mlx4_en: Add accelerated RFS support") Signed-off-by: Aya Levin <ayal@nvidia.com> Signed-off-by: Tariq Toukan <tariqt@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net>