Remove bogus disconnect test introduced by 95bef012e ("USB: more serial
drivers writing after disconnect") which prevented queued data from
being freed on disconnect.
The possible IO it was supposed to prevent is long gone.
Signed-off-by: Johan Hovold <jhovold@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>