USB: fix paths in usbmon documentation

Hi there.

On Aug 21 2009, Alan Stern wrote:
> On Thu, 20 Aug 2009, Rogério Brito wrote:
> > Again, just reiterating, what I said before, even though I am not sure
> > if I can reproduce it, I will try to.
> 
> A usbmon trace showing what happens when you plug in the drive and 
> when you run smartctl would help.

The documentation for usbmon in the kernel 2.6.31-rc7 kernel doesn't
match what the kernel exposes in the debug fs tree. This patch fixes it.
Signed-off-by: Rogério Brito <rbrito@ime.usp.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Documentation/usb/usbmon.txt

@@ -33,7 +33,7 @@ if usbmon is built into the kernel.
 
 Verify that bus sockets are present.
 
-# ls /sys/kernel/debug/usbmon
+# ls /sys/kernel/debug/usb/usbmon
 0s  0u  1s  1t  1u  2s  2t  2u  3s  3t  3u  4s  4t  4u
 #
 
@@ -58,11 +58,11 @@ Bus=03 means it's bus 3.
 
 3. Start 'cat'
 
-# cat /sys/kernel/debug/usbmon/3u > /tmp/1.mon.out
+# cat /sys/kernel/debug/usb/usbmon/3u > /tmp/1.mon.out
 
 to listen on a single bus, otherwise, to listen on all buses, type:
 
-# cat /sys/kernel/debug/usbmon/0u > /tmp/1.mon.out
+# cat /sys/kernel/debug/usb/usbmon/0u > /tmp/1.mon.out
 
 This process will be reading until killed. Naturally, the output can be
 redirected to a desirable location. This is preferred, because it is going