int i2o_install_handler (struct i2o_handler * h);
Install an I2O handler - these handle the asynchronous messaging from the card once it has initialised. If the table of handlers is full then -ENOSPC is returned. On a success 0 is returned and the context field is set by the function. The structure is part of the system from this time onwards. It must not be freed until it has been uninstalled