hwmon: (tmp102) add hibernation callbacks

Setting a dev_pm_ops suspend/resume pair but not a set of
hibernation functions means those pm functions will not be
called upon hibernation.
Fix this by using SIMPLE_DEV_PM_OPS, which appropriately
assigns the suspend and hibernation handlers and move
mp102_suspend/tmp102_resume under CONFIG_PM_SLEEP to avoid
build warnings.

Signed-off-by: Grygorii Strashko <Grygorii.Strashko@linaro.org>
[groeck: Declare tmp102_dev_pm_ops as static variable]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>