ASoC: es8316: fix null pointer error

due to function will be called from rk_headset_irq_hook_adc.c
when es8316 configured in defconfig file but not in device tree

Change-Id: Ie0294fff2c05b9f77c6740d81dc9445007c1b62b
Signed-off-by: zhangjun <zhangjun@rock-chips.com>

sound/soc/codecs/es8316.c

@@ -1003,7 +1003,12 @@ static irqreturn_t es8316_irq_handler(int irq, void *data)
  */
 int es8316_headset_detect(int jack_insert)
 {
-	struct es8316_priv *es8316 = snd_soc_codec_get_drvdata(es8316_codec);
+	struct es8316_priv *es8316;
+
+	if (!es8316_codec)
+		return -1;
+
+	es8316 = snd_soc_codec_get_drvdata(es8316_codec);
 
 	es8316->hp_inserted = jack_insert;