commit 24a85bae upstream.

wdm_flush() returns unsanitized USB error codes.
They must be cleaned up to before being anded to user space
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>