Default policy in neutron doesn't allow port security to change
if network not owned by the user. To allow users to update other
attributes of a port don't send port_security_enabled attribute
to neutron unless it changes.

If user tries to change port security on a port in a network not
owned by them it will still error as it does now.

Partial-Bug: #1841050

Change-Id: I301336103cabc3f1cab3ee72d7743385ff1a10d6
(cherry picked from commit d059b0bc)