net/mlx5e: Move RSS params to a dedicated struct

Remove RSS params from params struct under channels, and introduce
a new struct with RSS configuration params under priv struct. There is
no functional change here.

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