drivers/hwmon: switch to using input_dev->dev.parent

In preparation for struct class_device -> struct device input core
conversion, switch to using input_dev->dev.parent when specifying device
position in sysfs tree.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>