thermal/drivers/cpufreq_cooling: Update cpufreq_state only if state has changed

If state has not changed successfully and we updated cpufreq_state,
next time when the new state is equal to cpufreq_state (not changed
successfully last time), we will return directly and miss a
freq_qos_update_request() that should have been.

Fixes: 5130802d ("thermal: cpu_cooling: Switch to QoS requests for freq limits")
Cc: v5.4+ <stable@vger.kernel.org> # v5.4+
Signed-off-by: Zhuguangqing <zhuguangqing@xiaomi.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20201106092243.15574-1-zhuguangqing83@gmail.com