This cleans up the delay code by moving the timer-specific
implementations into the timer_ops struct.  Thus, rather then doing:

	if(x86_delay_tsc)
		__rdtsc_delay(loops);
	else if(x86_delay_cyclone)
		__cyclone_delay(loops);
	else if(whatever....

we just simply do:

	timer->delay(loops);

Making it much easier to accommodate alternate time sources.