soc: mediatek: Drop owner assignment from platform_driver

platform_driver does not need to set an owner because
platform_driver_register() will set it.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>