Device attribute does not have dotted "portAddr" format. Instead it
has single number format described but "usbAddr" which corresponds
to device parsing code in virDomainHostdevSubsysUSBDefParseXML.

Looks like [1] mistakenly changed device format for hostdev devices.
And [2] copy-n-paste this for hostdev network interfaces.

[1] 31710a53 Modify USB port to be defined as a port path
[2] 3b1c191f conf: parse/format type='hostdev' network interfaces
Signed-off-by: NNikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>