RDMA/mlx5: Initialize ib_device_ops struct

Initialize ib_device_ops with the supported operations using
ib_set_device_ops().
Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>