clocksource/drivers/c-sky: fixup qemu fail to bootup sometimes.

Timer startup must after timer_irq_enable. For qemu, timer tick
irq hanppens but irq not enable, so it will cause qemu boot failed.

Signed-off-by: Guo Ren <[e-mail]>
Tested-by: Liu Zhiwei <[e-mail]>

drivers/clocksource/timer-mp-csky.c

···
 
 	to->clkevt.cpumask = cpumask_of(cpu);
 
+	enable_percpu_irq(csky_mptimer_irq, 0);
+
 	clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
 					2, ULONG_MAX);
-
-	enable_percpu_irq(csky_mptimer_irq, 0);
 
 	return 0;
 }