cpufreq: Refactor cpufreq_set_policy()

Reduce the rampant usage of goto and the indentation level in
cpufreq_set_policy() to improve the readability of that code.

No functional changes should result from that.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>