ACPI: Mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/dock.c

@@ -482,6 +482,7 @@ int dock_notify(struct acpi_device *adev, u32 event)
 		surprise_removal = 1;
 		event = ACPI_NOTIFY_EJECT_REQUEST;
 		/* Fall back */
+		/* fall through */
 	case ACPI_NOTIFY_EJECT_REQUEST:
 		begin_undock(ds);
 		if ((immediate_undock && !(ds->flags & DOCK_IS_ATA))