Create instance ip only if subnet is available.

Change-Id: I2aee296f8e140b3bda2f6bb7600ecd1c4ba7a834
Closes-Bug: 1360876
(cherry picked from commit 7d1dd73e8017942a4d2089b4ea4f162f0df245f7)
Merge "Create instance ip only if subnet is available." into R1.10