drivers/greybus: Use kobj_to_dev()

Use kobj_to_dev() instead of container_of()

Signed-off-by: Wang Qing <wangqing@vivo.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/1597289690-22857-1-git-send-email-wangqing@vivo.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>