net/mlx5e: Union RQ RX info per RQ type

We have two types of RX RQs, and they use two separate sets of
info arrays and structures in RX data path function.  Today those
structures are mutually exclusive per RQ type, hence one kind is
allocated on RQ creation according to the RQ type.

For better cache locality and to minimalize the
sizeof(struct mlx5e_rq), in this patch we define them as a union.

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>