OMAPDSS: HDMI: Split audio_enable into audio_enable/disable

To improve readability, split the audio_enable HDMI IP operation
into two separate functions for enabling and disabling audio.
The audio_enable function is also modified to return an error value.

While there, update these operations for the OMAP4 IP accordingly.

Signed-off-by: Ricardo Neri <ricardo.neri@ti.com>
diff --git a/drivers/video/omap2/dss/hdmi.c b/drivers/video/omap2/dss/hdmi.c
index 5f2e2f6..2a01140 100644
--- a/drivers/video/omap2/dss/hdmi.c
+++ b/drivers/video/omap2/dss/hdmi.c
@@ -557,12 +557,12 @@
 	case SNDRV_PCM_TRIGGER_START:
 	case SNDRV_PCM_TRIGGER_RESUME:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
-		ip_data->ops->audio_enable(ip_data, true);
+		ip_data->ops->audio_enable(ip_data);
 		break;
 	case SNDRV_PCM_TRIGGER_STOP:
 	case SNDRV_PCM_TRIGGER_SUSPEND:
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
-		ip_data->ops->audio_enable(ip_data, false);
+		ip_data->ops->audio_disable(ip_data);
 		break;
 	default:
 		err = -EINVAL;