thermal: cpu_cooling: fix improper order during initialization

The freq_table array is not populated before calling
thermal_of_cooling_register. The code which populates the freq table was
introduced in commit f6859014.
This should be done before registering new thermal cooling device.
The log shows effects of this wrong decision.
[    2.172614] cpu cpu1: Failed to get voltage for frequency 1984518656000: -34
[    2.220863] cpu cpu0: Failed to get voltage for frequency 1984524416000: -34

Cc: <stable@vger.kernel.org> # 3.19+
Fixes: f6859014 ("thermal: cpu_cooling: Store frequencies in descending order")
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Acked-by: Javi Merino <javi.merino@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>