Do not try to reserve the address if it is same as gateway ip. Gateway ip is already reserved at the time of subnet creation.

Change-Id: Id763db6d20620dd820443ffb619c0fb66c0b8190
Closes-Bug: 1372384
(cherry picked from commit aad6d3ed51f1c97fde9403f893b59011aacf4a85)
Merge "Do not try to reserve the address if it is same as gateway ip. Gateway ip is already reserved at the time of subnet creation." into R1.10