legacy netvirt: forcibly disable port security for network port

legacy netvirt: forcibly disable port security for network port

Security group applies to only VM port. Not to internal used port.
router interface port, dhc port and floating ip port.
which can be identified by its device owner.
"network:{routerxxx, dhcp, floatingip}"
It can be realized by forcibly disabling port security on those port.

With port security extension enabled, neutron disabled port security.
The extension is, however, optional, so ODL shouldn't depend on it.

Partial-bug: #7128
Change-Id: I3295ebc0e77d387cdfb80be318ef048ba9763994
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
(cherry picked from commit 5da83fc96656d5be54b3451a2f221a2e780e52d4)