cpufreq: mvebu: Remove OPPs using dev_pm_opp_remove()

dev_pm_opp_cpumask_remove_table() is going to change in the next commit
and will not remove dynamic OPPs automatically. They must be removed
with a call to dev_pm_opp_remove().

Reviewed-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>