USB: Fix 'bad dma' problem on WDM device disconnect

In the WDM class driver a disconnect event leads to calls to
usb_free_coherent to put back two USB DMA buffers allocated earlier.
The call to usb_free_coherent uses a different size parameter
(desc->wMaxCommand) than the corresponding call to usb_alloc_coherent
(desc->bMaxPacketSize0).

When a disconnect event occurs, this leads to 'bad dma' complaints
from usb core because the USB DMA buffer is being pushed back to the
'buffer-2048' pool from which it has not been allocated.

This patch against the most recent linux-2.6 kernel ensures that the
parameters used by usb_alloc_coherent & usb_free_coherent calls in
cdc-wdm.c match.

Signed-off-by: Robert Lukassen <robert.lukassen@tomtom.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/class/cdc-wdm.c

@@ -281,7 +281,7 @@ static void cleanup(struct wdm_device *desc)
 			  desc->sbuf,
 			  desc->validity->transfer_dma);
 	usb_free_coherent(interface_to_usbdev(desc->intf),
-			  desc->wMaxCommand,
+			  desc->bMaxPacketSize0,
 			  desc->inbuf,
 			  desc->response->transfer_dma);
 	kfree(desc->orq);