pm: use actions for device PM control

Instead of passing target states, use actions for device PM control.
Actions represent better the meaning of the callback argument.
Furthermore, they are more future proof as they can be suitable for
other PM actions that have no direct mapping to a state. If we compare
with Linux, we could have a multi-stage suspend/resume. Such scenario
would not have a good mapping when using target states.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

include/pm/device.h

@@ -70,6 +70,16 @@ enum pm_device_flag {
 	PM_DEVICE_FLAG_COUNT
 };
 
+/** @brief Device PM actions. */
+enum pm_device_action {
+	/** Suspend. */
+	PM_DEVICE_ACTION_SUSPEND,
+	/** Resume. */
+	PM_DEVICE_ACTION_RESUME,
+	/** Turn off. */
+	PM_DEVICE_ACTION_TURN_OFF,
+};
+
 /**
  * @brief Device PM info
  */
@@ -97,14 +107,14 @@ struct pm_device {
  * @brief Device power management control function callback.
  *
  * @param dev Device instance.
- * @param state Requested state.
+ * @param action Requested action.
  *
  * @retval 0 If successful.
- * @retval -ENOTSUP If the requested state is not supported.
+ * @retval -ENOTSUP If the requested action is not supported.
  * @retval Errno Other negative errno on failure.
  */
 typedef int (*pm_device_control_callback_t)(const struct device *dev,
-					    enum pm_device_state state);
+					    enum pm_device_action action);
 
 /**
  * @brief Get name of device PM state