qemu: call networkPlugBandwidth() for all types of network

qemu: call networkPlugBandwidth() for all types of network

To fix the actual bug, it was necessary to make networkPlugBandwidth() be
called also for 'bridge'-type networks implemented using macvtap's 'bridge'
mode (previously it was only called for those implemented on top of an
existing bridge).

However, it seems beneficial to call it for other network types as well, at
least because it removes an inconsistency in types of bandwidth configuration
changes permissible in inactive and active domain configs.  It should also be
safe as the function pretty much amounts to NOP if no QoS is requested and the
new behaviour should not be any worse than before if it is.

Signed-off-by: Pavel Mores <pmores@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>