cpufreq: Avoid hardcoding device tree paths for CPU

Hardcoded devicetree paths don't work well with multi cluster cpus.
Instead get the device node associated with each logical CPU.

Change-Id: I1942d6a13aff4a3840d92145377dcfd87dfc66d9
Signed-off-by: Ravi Vembu <raviv@motorola.com>
Reviewed-on: http://gerrit.mot.com/779540


SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver <sltawvr@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Ravi Chebolu <arc095@motorola.com>