i2c: use kobj_to_dev() API

Use kobj_to_dev() API instead of container_of().

Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
Reviewed-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>