cpufreq: arm_big_little: free OPP table created during ->init()

OPP layer now supports freeing of OPPs and we should free them once they aren't
useful anymore.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge branch 'pm-cpufreq' into linux-next

* pm-cpufreq:
  cpufreq: arm_big_little: free OPP table created during ->init()
  imx6q: free OPP table created during ->init()
  exynos5440: free OPP table created during ->init()
  cpufreq-dt: free OPP table created during ->init()