Although the serial, parallel, chanel, input & fs devices do
not have PCI address info, they can all have device aliases.
Thus it neccessary to associate the virDomainDeviceInfo data
with them all.

* src/conf/domain_conf.c, src/conf/domain_conf.h: Add hooks for
  parsing / formatting device info for serial, parallel, channel
  input and fs devices.
* docs/schemas/domain.rng: Associate device info with character
  devices, input & fs device