RDMA/mlx5: Get ECE options from FW during create QP

Supported ECE options are returned from FW in the create_qp phase and zero
means that field is not valid. Such default value allows us to reuse
reserved field without worries about comp_mask.

Update create QP API to return ECE options.

Link: https://lore.kernel.org/r/20200526115440.205922-3-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>