USB: hub_for_each_child should skip unconnected ports

This patch (as1619) improves the interface to the "hub_for_each_child"
macro.  The name clearly suggests that the macro iterates over child
devices; it does not suggest that the loop will also iterate over
unnconnected ports.

The patch changes the macro so that it will skip over unconnected
ports and iterate only the actual child devices.  The two existing
call sites are updated to avoid testing for a NULL child pointer,
which is now unnecessary.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/usb.h b/include/linux/usb.h
index f92cdf0..5df7c87 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -588,8 +588,9 @@
  */
 #define usb_hub_for_each_child(hdev, port1, child) \
 	for (port1 = 1,	child =	usb_hub_find_child(hdev, port1); \
-		port1 <= hdev->maxchild; \
-		child = usb_hub_find_child(hdev, ++port1))
+			port1 <= hdev->maxchild; \
+			child = usb_hub_find_child(hdev, ++port1)) \
+		if (!child) continue; else
 
 /* USB device locking */
 #define usb_lock_device(udev)		device_lock(&(udev)->dev)