sched/tick: Ensure timers does not get queued on isolated cpus

Timers should not be queued on isolated cpus. Instead try to find
other cpus to queue timer on.

Change-Id: I7a1a8aade8630226d7349cc37afd1a3abe48fc67
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>