[CPUFREQ] Mark policy_rwsem as going static in cpufreq.c wont be exported

lock_policy_rwsem_* and unlock_policy_rwsem_* routines in cpufreq.c are
currently exported to drivers. Improper use of those locks can
result in deadlocks and it is better to keep the locks localized.
Two previous in-kernel users of these interfaces (ondemand and conservative),
do not use this interfaces any more. Schedule them for removal.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>