net/mlx5e: Remove RQ MPWQE fields from params

Introduce functions to calculate them when needed.
They can be derived from other params.
This will simplify transition between RQ configurations.

In general, any parameter that is not explicitly set
or controlled, but derived from other parameters,
should not have a control-path field itself, but a
getter function.

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