hrtimer: remove hrtimer_clock_base::get_softirq_time()

Peter Zijlstra noticed this 8 months ago and I just noticed
it again.

hrtimer_clock_base::get_softirq_time() is currently unused
in the entire tree. In fact, looking at the logs, it appears
as if it was never used. Remove it.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/hrtimer.c

@@ -1401,9 +1401,7 @@ void hrtimer_run_queues(void)
 		if (!base->first)
 			continue;
 
-		if (base->get_softirq_time)
-			base->softirq_time = base->get_softirq_time();
-		else if (gettime) {
+		if (gettime) {
 			hrtimer_get_softirq_time(cpu_base);
 			gettime = 0;
 		}