cpufreq: mvebu: Free the clock reference in the normal path

In case of error the clock reference was freed but not in normal path
once it was nor more used. This patch fixes it.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>