model.host: changing listDevices() to listAllDevices()

The method listDevices() has unexpected behavior in certain
situations and architectures. According the libvirt API,
listAllDevices() delivers more control over the results and
it does not present the same problems.

For those reasons, this commit changes all the occurences of
listDevices() to use listAllDevices() instead.

Signed-off-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>