RDMA/mlx5: Set ECE options during QP create

Allow users to ask creation of QPs with specific ECE options.  Such early
set even before RDMA-CM connection is established is useful if user knows
exactly which option he needs.

Link: https://lore.kernel.org/r/20200526115440.205922-4-leon@kernel.org


Reviewed-by: Mark Zhang <markz@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>