bridge: Always delete the correct interfaces in port_del_ifaces().

bridge: Always delete the correct interfaces in port_del_ifaces().

This code was checking a name from cfg->interfaces[i] but using the result
to decide whether to delete port->ifaces[i].  The two arrays aren't
necessarily in the same order so this code could delete the wrong iface.

Found by inspection.  This is probably not a common problem in practice
because I imagine that deleting an interface from a bond, without deleting
the bond itself, is a rare operation.  The problem would also be
intermittent--after a few switch reconfiguration cycles I imagine that
the problem would resolve.