ALSA: aloop: Use setup_timer() and mod_timer()

No functional change, refactoring with the standard helpers.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/aloop.c

@@ -181,8 +181,7 @@ static void loopback_timer_start(struct loopback_pcm *dpcm)
 	}
 	tick = dpcm->period_size_frac - dpcm->irq_pos;
 	tick = (tick + dpcm->pcm_bps - 1) / dpcm->pcm_bps;
-	dpcm->timer.expires = jiffies + tick;
-	add_timer(&dpcm->timer);
+	mod_timer(&dpcm->timer, jiffies + tick);
 }
 
 /* call in cable->lock */