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

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

commit 878b753e32ca765cd346a5d3038d630178ec78ff upstream.
[ changed s/usb_free_coherent/usb_buffer_free/ for 2.6.32.x]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Bjørn Mork <bjorn@mork.no>