cpufreq: CPPC: Don't warn if FIE init fails to read counters

cpufreq: CPPC: Don't warn if FIE init fails to read counters

During the CPPC FIE initialization, reading perf counters on offline cpus
should be expected to fail.  Don't warn on this case.

Also, change the error log level to debug since FIE is optional.

Co-developed-by: Bowen Yu <yubowen8@huawei.com>
Signed-off-by: Bowen Yu <yubowen8@huawei.com> # Changing loglevel to debug
Signed-off-by: Jie Zhan <zhanjie9@hisilicon.com>
[ Viresh: Added back the dropped comment. ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>