cpufreq: mediatek-hw: Register to module device table

Register the compatibles for this module on the module device table so
it can be automatically loaded when a matching device is found on the
system.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>