net/mlx5e: Use a new initializer to build uniform indir table

Replace mlx5e_build_default_indir_rqt with a new initializer of struct
mlx5e_rss_params_indir that works directly with the struct, rather than
its internals.

The new initializer is called mlx5e_rss_params_indir_init_uniform, which
also reflects the purpose (uniform spreading) better.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>