core_ctl: fix bug in assignment of not_preferred tunable values

Cluster's lru list is iterated while storing the not_preferred
tunable values. The position of a CPU in this list gets changed
when it is isolated. This results in an incorrect assignment of
user input. Fix this by iterating the CPUs serially in a cluster.

Change-Id: I7235ca981b0fd82488034ab8d1880bb7498c9a72
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>