hwmon: (ltc2947) Switch to EXPORT_SIMPLE_DEV_PM_OPS() and pm_sleep_ptr()

These newer PM macros allow the compiler to see what code it can remove
if !CONFIG_PM_SLEEP. This allows the removal of __maybe_unused markings
whilst achieving the same result. In this case it also lets the
structure itself be removed.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220925172759.3573439-9-jic23@kernel.org


Signed-off-by: Guenter Roeck <linux@roeck-us.net>