ACPI: Get acpi_device's parent from the parent field

Printk modifier %pfw is used to print the full path of the device name.
This is obtained device by device until a device no longer has a parent.

On ACPI getting the parent fwnode is done by calling acpi_get_parent()
which tries to down() a semaphore. But local IRQs are now disabled in
vprintk_store() before the mutex is acquired. This is obviously a problem.

Luckily struct device, embedded in struct acpi_device, has a parent field
already. Use that field to get the parent instead of relying on
acpi_get_parent().

Fixes: 3bd32d6a ("lib/vsprintf: Add %pfw conversion specifier for printing fwnode names")
Cc: 5.5+ <stable@vger.kernel.org> # 5.5+
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/property.c

@@ -1090,15 +1090,10 @@ struct fwnode_handle *acpi_node_get_parent(const struct fwnode_handle *fwnode)
 		/* All data nodes have parent pointer so just return that */
 		return to_acpi_data_node(fwnode)->parent;
 	} else if (is_acpi_device_node(fwnode)) {
-		acpi_handle handle, parent_handle;
+		struct device *dev = to_acpi_device_node(fwnode)->dev.parent;
 
-		handle = to_acpi_device_node(fwnode)->handle;
-		if (ACPI_SUCCESS(acpi_get_parent(handle, &parent_handle))) {
-			struct acpi_device *adev;
-
-			if (!acpi_bus_get_device(parent_handle, &adev))
-				return acpi_fwnode_handle(adev);
-		}
+		if (dev)
+			return acpi_fwnode_handle(to_acpi_device(dev));
 	}
 
 	return NULL;