conf: use virDeviceHostdevPCIDriverInfo in network and networkport objects

conf: use virDeviceHostdevPCIDriverInfo in network and networkport objects

The next step in consolidating parsing/formatting of the <driver>
element of these objects using a common struct and common code. This
eliminates the virNetworkForwardDriverNameType enum which is nearly
identical to virDeviceHostdevPCIDriverName (the only non-identical bit
was just because they'd gotten out of sync over time) and replaces its
uses with a virDeviceHostdevPCIDriverInfo (which is a struct that
contains a virDeviceHostdevPCIDriverName).

Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>