[PATCH] alpha: interrupt/preempt update [6/10]

[PATCH] alpha: interrupt/preempt update [6/10]

This one is large mostly because of massive code deletion.
- cli, sti an so on go away;
- irq_smp.c goes to /dev/null; the only leftover (synchronize_irq)
  moved to irq.c;
- hardirq count field in the preemption counter extended to 12 bits -
  one more than required for wildfire.