cpufreq: Remove unused for_each_policy macro

Macro 'for_each_policy' has become unused since commit
f963735a ("cpufreq: Create for_each_{in}active_policy()"), so
remove it.

Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>