ACPI / platform / LPSS: Enable async suspend/resume of LPSS devices

To seed up suspend and resume of devices included into Intel SoCs
handled by the ACPI LPSS driver during system suspend, make
acpi_lpss_create_device() call device_enable_async_suspend() for
every device created by it.

This requires acpi_create_platform_device() to be modified to return
a pointer to struct platform_device instead of an int.  As a result,
acpi_create_platform_device() cannot be pointed to by the .attach
pointer in platform_handler directly any more, so a simple wrapper
around it is necessary for this purpose.  That, in turn, allows the
second unused argument of acpi_create_platform_device() to be
dropped, which is an improvement.

Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 9573913..bb7de41 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -180,8 +180,7 @@
   -------------------------------------------------------------------------- */
 struct platform_device;
 
-int acpi_create_platform_device(struct acpi_device *adev,
-				const struct acpi_device_id *id);
+struct platform_device *acpi_create_platform_device(struct acpi_device *adev);
 
 /*--------------------------------------------------------------------------
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