timer: reduce cache bouncing of deferral timer wheel

Commit a40f7521 (timer: make deferrable cpu unbound timers really not
bound to a cpu) made any non-idle CPUs in the system can service expired
deferral timer entries.  This means deferral timer entries can be
serviced as early as possible after it expires but in many cases it's
suboptimal since switching the CPU of timer wheel incurs a cache
bouncing/synchronization cost.

Reduce cache bouncing by servicing the deferrable timer wheel with timer
tick CPU as it doesn't bounce as often but still guarantees to run timer
softirq when there is any CPU that isn't idle.

CRs-fixed: 815184
Change-Id: I6d51390832538ad90eccf459e90bff0b25aad09f
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>