RDMA/mlx5: Refactor raw flow creation

Move struct mlx5_flow_act to be passed from the method entry point,
this will allow to add support for flow action for the raw create flow
path.

Signed-off-by: Mark Bloch <markb@mellanox.com>
Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>