PM / devfreq: Fix kernel warning with cpufreq passive register fail

Remove cpufreq_passive_unregister_notifier from
cpufreq_passive_register_notifier in case of error as devfreq core
already call unregister on GOV_START fail.

This fix the kernel always printing a WARN on governor PROBE_DEFER as
cpufreq_passive_unregister_notifier is called two times and return
error on the second call as the cpufreq is already unregistered.

Fixes: a03dacb0 ("PM / devfreq: Add cpu based scaling support to passive governor")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>