net/mlx5e: Move XDP SQ instance into RQ

To save many rq->channel->sq dereferences in fast-path.
And rename it to xdpsq.

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