We allow translation from no_bandwidth to has_bandwidth for a vnic.
However, going in the opposite direction is not implemented. It's not
limitation of the API rather than internal implementation. The problem
is, we correctly detect that user hasn't specified any outbound (say
he wants to clear out outbound). However, this gets overwritten by
current vnic outbound settings. Then, virNetDevBandwidthSet doesn't
change anything. We need to stop overwriting the outbound if users
don't want us to. Same applies for inbound.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>