cpufreq: drop owner assignment from platform_drivers

A platform_driver does not need to set an owner, it will be populated by the
driver core.

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
(cherry picked from commit 30f51f248c1d0987733353b64adae26b23165908)
Signed-off-by: Alex Shi <alex.shi@linaro.org>