Add test to port_security to test with security_groups

This patch adds a missing testcase to the port_security tests to test
for creating a port with port_security_enabled=False and passing in
a security group.

Closes-bug: #1267246
Change-Id: Ifb5a5571f016a5d7c5b5075c97dc27279cd79bb7
Merge "Add test to port_security to test with security_groups"