- tipar_open(): fix unsigned comparison

- tipar_open(): don't permit NULL pardevice (probably unneeded given the
  above fix).

- tipar_init_module(): handle the situation where parport_register_driver()
  failed to register any devices (parport_register_driver() drops the ->attach
  return value on the floor).

  This probably makes fixes #1 and #2 unneeded.

- tipar_init_module(): fix various error-path resource leaks.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>