cpuidle: lpm-levels: Core isolation check to get PM QoS latency

Check the core isolation to get PM QoS request on that core while
it going to lpm. If its an isolated core pass long latency so
that core can select deeper lpm state.

Change-Id: Iafbfb75c484d602eb37bcd702e83371fd97362fd
Signed-off-by: Raghavendra Kakarla <rkakarla@codeaurora.org>