This reverts commit d3b8f505.

The commit introduced a problem that "File exists" will be reported
when trying to open br0.

The operation that adds eth0 to br0 while moving IP address from
eth0 to bridge internal interface br0 reproduces this issue.

$ ip a del <ip> dev eth0; ip a add <ip> dev br0; ovs-vsctl add-port br0 eth0
$ ovs-dpctl show
...
port 1: br0 (internal: open failed (File exists))
...

At this point restarting OVS will result in connection lost for the
node.

Reverting the change fixes the problem. Since adding physical interface
to OVS bridge is quite normal operation, the problem is more severe
than the original problem fixed by commit d3b8f505

, so revert this
before a better fix is found for the original problem.

Signed-off-by: Han Zhou <zhouhan@gmail.com>
Signed-off-by: Justin Pettit <jpettit@ovn.org>