defconfig: msm8909w: Disable KSM

KSM is not needed for msm8909w, hence disable it for debug
defconfig and it is already disabled in perf defconfig.

CRs-fixed: 973339
Change-Id: I8730f993932267175e42021c87b147a68c788a0d
Signed-off-by: Shiraz Hashim <shashim@codeaurora.org>