hotplug: Resolve Coverity FORWARD_NULL

hotplug: Resolve Coverity FORWARD_NULL

Coverity complained that because the cfg->macFilter call checked
net->ifname != NULL before calling ebtablesRemoveForwardAllowIn, then
the virNetDevOpenvswitchRemovePort call should have the same check.

However, if I move the ebtables call prior to the check for TYPE_DIRECT
(where there is a VIR_FREE(net->ifname)), then it seems Coverity is
happy.  Since firewall info is tacked on last during setup, removing
it in the opposite order of initialization seems to be natural anyway