If you wish to use the network interface facilities of the driver, then you need to attach a network device to each channel that is present and in use. In addition to use the generic HDLC you need to follow some additional plumbing rules. They may seem complex but a look at the example hostess_sv11 driver should reassure you.
The network device used for each channel should be pointed to by the netdevice field of each channel. The hdlc-> priv field of the network device points to your private data - you will need to be able to find your private data from this.
The way most drivers approach this particular problem is to create a structure holding the Z8530 device definition and put that into the private field of the network device. The network device fields of the channels then point back to the network devices.
If you wish to use the generic HDLC then you need to register the HDLC device.
Before you register your network device you will also need to provide suitable handlers for most of the network device callbacks. See the network device documentation for more details on this.