usb serial decrements the pm counter even if an interface has been
disconnected. If it was a logical disconnect the interface may belong
already to another driver. This patch introduces a check for disconnected
interfaces.
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Cc: Stable <stable@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>