[PATCH] usbfs: use the correct signal number for disconnection

usbfs stores the wrong signal number in the siginfo structure used for
notifying user programs about device disconnect.  This patch (as726)
fixes it.

From: Zoran Marceta <Zoran.Marceta@micronasnit.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>