defconfig: Enable KSM for perf_defconfigs of 1GB targets for L&M

Default defconfig for Lean and Mean builds will be perf defconfig.
KSM is enabled with Lean and Mean builds.

Change-Id: Iaa6c21bec482870d649209cbefef83c95ca905c2
CRs-Fixed: 798944
Signed-off-by: Kishore Srivenkata Ganesh Bolisetty <bsrivenk@codeaurora.org>