cpufreq: Print driver name if cpufreq_suspend() fails

Instead of printing the policy, which is incidentally a kernel pointer,
so with limited interest, print the cpufreq driver name that failed to
be suspend, which is more useful for debugging.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>