driver core / ACPI: Represent ACPI companions using fwnode_handle

Now that we have struct fwnode_handle, we can use that to point to
ACPI companions from struct device objects instead of pointing to
struct acpi_device directly.

There are two benefits from that.  First, the somewhat ugly and
hackish struct acpi_dev_node can be dropped and, second, the same
struct fwnode_handle pointer can be used in the future to point
to other (non-ACPI) firmware device node types.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
diff --git a/drivers/acpi/dock.c b/drivers/acpi/dock.c
index d9339b4..a688aa2 100644
--- a/drivers/acpi/dock.c
+++ b/drivers/acpi/dock.c
@@ -615,7 +615,7 @@
 	memset(&pdevinfo, 0, sizeof(pdevinfo));
 	pdevinfo.name = "dock";
 	pdevinfo.id = dock_station_count;
-	pdevinfo.acpi_node.companion = adev;
+	pdevinfo.fwnode = acpi_fwnode_handle(adev);
 	pdevinfo.data = &ds;
 	pdevinfo.size_data = sizeof(ds);
 	dd = platform_device_register_full(&pdevinfo);