add missing deprecation reason for eventlet option
add missing deprecation reason for eventlet option

In ac039414ce997cfcafa09efa9e089e09c3058b70 merged it was missing
a deprecation reason for admin_port.

Change-Id: I13365000afbe3bbf6859525dea901c32c4508b95

openstack/keystone,mahak/keystone,mahak/keystone,ilay09/keystone,openstack/keystone,ilay09/keystone,rajalokan/keystone,cernops/keystone,cernops/keystone,openstack/keystone,mahak/keystone,ilay09/keystone,rajalokan/keystone,rajalokan/keystone