ovs-vsctl command "--if-exists del-port eth0" does nothing if eth0 is on
a bridge as part of a bond, because the bond's port name is not eth0 but
something else. But interface-reconfigure needs to do that, so this commit
adds that ability to ovs-vsctl and modifies interface-reconfigure to use it.
Signed-off-by: Ben Pfaff <blp@nicira.com>
7c79588e00