ASoC: Report IRQ_NONE when we don't see an interrupt from WM8962

This should never happen with level triggered IRQs.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
diff --git a/sound/soc/codecs/wm8962.c b/sound/soc/codecs/wm8962.c
index 75e7840..add07ff 100644
--- a/sound/soc/codecs/wm8962.c
+++ b/sound/soc/codecs/wm8962.c
@@ -3570,6 +3570,9 @@
 	active = snd_soc_read(codec, WM8962_INTERRUPT_STATUS_2);
 	active &= ~mask;
 
+	if (!active)
+		return IRQ_NONE;
+
 	/* Acknowledge the interrupts */
 	snd_soc_write(codec, WM8962_INTERRUPT_STATUS_2, active);