In an external network, even though a floatingIP is reserved, it can be created as an InstanceIP.
This patch corrects that bug

Backported from master

Closes-bug: #1368691

Change-Id: Ifc2203a05901f03a787fb3652c07de0e09542017
Merge "In an external network, even though a floatingIP is reserved, it can be created as an InstanceIP. This patch corrects that bug" into R1.10