USB: fix interface sysfs file-creation bug

This patch (as1005) fixes a rather subtle problem.  When
usb_set_configuration() registers the interfaces and their files in
sysfs, it doesn't expect those files to exist already.  But when an
interface is registered, its driver may call usb_set_interface() and
thereby cause the sysfs files to be created.  The result is an error
when usb_set_configuration() goes on to create those same files again.

The (not-so-great) solution is to have usb_set_configuration() remove
any existing files before creating them.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/message.c

@@ -1641,7 +1641,13 @@ int usb_set_configuration(struct usb_device *dev, int configuration)
 				intf->dev.bus_id, ret);
 			continue;
 		}
-		usb_create_sysfs_intf_files (intf);
+
+		/* The driver's probe method can call usb_set_interface(),
+		 * which would mean the interface's sysfs files are already
+		 * created.  Just in case, we'll remove them first.
+		 */
+		usb_remove_sysfs_intf_files(intf);
+		usb_create_sysfs_intf_files(intf);
 	}
 
 	usb_autosuspend_device(dev);