opp: Reduce the size of critical section in _opp_table_kref_release()

There is a lot of stuff here which can be done outside of the big
opp_table_lock, do that. This helps avoiding few circular dependency
lockdeps around debugfs and interconnects.

Reported-by: Rob Clark <robdclark@gmail.com>
Reported-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>