Fix typo in API error message.
Fix typo in API error message.

("foundfor" instead of "found for")

Mentioned in LP bug #1517111.

Change-Id: If76009817b7d9b0b2384acd12c8a1411dcbcb5b9
Partial-bug: 1517111

openstack/networking-bgpvpn,openstack/networking-bgpvpn,openstack/networking-bgpvpn