net/mlx5e: RX, Always prefer Linear SKB configuration

Prefer the linear SKB configuration of Legacy RQ over the
non-linear one of Striding RQ.

This implies that ConnectX-4 LX now uses legacy RQ by default,
as it does not support the linear configuration of Striding RQ.

Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>