OPP: Drop a redundant in-parameter to _set_opp_level()

The in-parameter "opp_table" isn't needed by _set_opp_level(). Let's
therefore drop it.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>