cpufreq: ti-cpufreq: Convert to module_platform_driver

ti-cpufreq will be responsible for calling dev_pm_opp_set_regulators on
platforms that require AVS and ABB regulator support so we must be
able to defer probe if regulators are not yet available, so change
ti-cpufreq to be a module_platform_driver to allow for probe defer.

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>