net/mlx5: Add ability to read and write ECE options

The end result of RDMA-CM ECE handshake is ECE options, which is
needed to be used while configuring data QPs. Such options can
come in any QP state, so add in/out fields to set and query
ECE options.

OUT fields:
* create_qp() - default ECE options for that type of QP.
* modify_qp() - enabled ECE options after QP state transition.

IN fields:
* create_qp() - create QP with this ECE option.
* modify_qp() - requested options. For unconnected QPs, the FW
will return an error if ECE is already configured with any options
that not equal to previously set.

Reviewed-by: Mark Zhang <markz@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>