msm: cpuidle: Update C state time stats in the cpu idle device.

msm_pm_idle_enter function returns time spent by cpu in particular
C state. Update the cpu idle device last residency with the return
value which is required for cpuidle stats.

CRs-fixed: 391456
Change-Id: If9f1b59e05c233e53ba37ae0fe9399f12275f3d8
Signed-off-by: Anji Jonnala <anjir@codeaurora.org>