Add "back" as a possible panel output when _PLD output from ACPI
indicates back panel.
Fixes: 6423d2951087 ("driver core: Add sysfs support for physical location of a device")
Signed-off-by: Won Chung <wonchung@google.com>
Link: https://lore.kernel.org/r/20220509214930.3573518-1-wonchung@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
        case DEVICE_PANEL_FRONT:
                panel = "front";
                break;
+       case DEVICE_PANEL_BACK:
+               panel = "back";
+               break;
        default:
                panel = "unknown";
        }