net/mlx5e: Move mlx5e_build_rss_params() call to init_rx

RSS params belong to the RX side initialization. Move them from
profile->init to profile->init_rx stage to allow the next commit to move
rss_params out of priv to a dynamically-allocated struct.

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