vmstat: Add cpu isolation awareness

Ensure vmstat updates do not run on isolated cpus.

Change-Id: Ie16cc9eb73b240459a9a385c39f3176b57d34950
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
[rameezmustafa@codeaurora.org: Port to msm-4.9]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>