iio: pressure: bmp280: Use new PM macros

Use the new EXPORT_RUNTIME_DEV_PM_OPS() macro. It allows the underlying
dev_pm_ops struct as well as the suspend/resume callbacks to be detected
as dead code in the case where CONFIG_PM is disabled, without having to
wrap everything inside #ifdef CONFIG_PM guards.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>