parisc: blink all or loadavg LEDs on oops

- depending on machine type, blink all leds or just the loadavg
  leds twice a second on oops.
- cancel_rearming_delayed_workqueue() is obsolete,
  use cancel_delayed_work_sync() instead

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>