ACPI: Add helper acpi_use_parent_companion

In several drivers devices use the ACPI companion of the parent.
Add a helper for this use case to avoid code duplication.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

include/linux/acpi.h

@@ -1539,4 +1539,9 @@ static inline void acpi_device_notify(struct device *dev) { }
 static inline void acpi_device_notify_remove(struct device *dev) { }
 #endif
 
+static inline void acpi_use_parent_companion(struct device *dev)
+{
+	ACPI_COMPANION_SET(dev, ACPI_COMPANION(dev->parent));
+}
+
 #endif	/*_LINUX_ACPI_H*/