net/mlx5: rearrange device attribute structure

net/mlx5: rearrange device attribute structure

Rearrange the mlx5_os_get_dev_attr() function in such a way that it
first executes the queries and only then updates the fields.
In addition, it changed its name in preparation for expanding its
operations to configure the capabilities inside it.

Signed-off-by: Michael Baum <michaelba@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>