ksm: Provide support to use deferred timers for scanner thread

KSM thread to scan pages is getting schedule on definite timeout.
That wakes up CPU from idle state and hence may affect the power
consumption. Provide an optional support to use deferred timer
which suites low-power use-cases.
To enable deferred timers,
$ echo 1 > /sys/kernel/mm/ksm/deferred_timer
Change-Id: I07fe199f97fe1f72f9a9e1b0b757a3ac533719e8
Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>

See: http://review.cyanogenmod.org/#/c/64706/
kowalski: defconfig: Update config

Change-Id: I6ef80b7c30a27b6cc74135cf09df73ad6dc61b41
mem: pksm: Change default values

Change-Id: If04b61c73cb34342710f83ec2813200225331aa4