core_ctl: Add a kernel parameter to disable core_ctl

Add a kernel parameter called "core_ctl_disable_cpumask" to
specify the CPUs for which core_ctl is not needed. As
core_ctl operates on a cluster basis, all of the CPUs in a
given cluster must be specified to disable core_ctl on that
cluster.

Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
[markivx: doc moved to Documentation/admin-guide/]
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>

Change-Id: I2468b10d4f8b1c9ddcdb8e2eb10124975a6a34d4
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>