RDMA: Rename port_callback to init_port

Most provider routines are callback routines which ib core invokes.
_callback suffix doesn't convey information about when such callback is
invoked. Therefore, rename port_callback to init_port.

Additionally, store the init_port function pointer in ib_device_ops, so
that it can be accessed in subsequent patches when binding rdma device to
net namespace.

Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/mlx4/main.c

@@ -2856,7 +2856,7 @@ static void *mlx4_ib_add(struct mlx4_dev *dev)
 
 	rdma_set_device_sysfs_group(&ibdev->ib_dev, &mlx4_attr_group);
 	ibdev->ib_dev.driver_id = RDMA_DRIVER_MLX4;
-	if (ib_register_device(&ibdev->ib_dev, "mlx4_%d", NULL))
+	if (ib_register_device(&ibdev->ib_dev, "mlx4_%d"))
 		goto err_diag_counters;
 
 	if (mlx4_ib_mad_init(ibdev))