ALSA: usb-audio: simplify control interface access

As the control interface is now carried in struct snd_usb_audio, we can
simplify the API a little and also drop the private ctrlif field from
struct usb_mixer_interface.

Also remove a left-over function prototype in pcm.h.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/format.c b/sound/usb/format.c
index 30364ab..4387f54 100644
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -264,13 +264,12 @@
  * on the audioformat table (audio class v2).
  */
 static int parse_audio_format_rates_v2(struct snd_usb_audio *chip,
-				       struct audioformat *fp,
-				       struct usb_host_interface *iface)
+				       struct audioformat *fp)
 {
 	struct usb_device *dev = chip->dev;
 	unsigned char tmp[2], *data;
 	int nr_triplets, data_size, ret = 0;
-	int clock = snd_usb_clock_find_source(chip, chip->ctrl_intf, fp->clock);
+	int clock = snd_usb_clock_find_source(chip, fp->clock);
 
 	if (clock < 0) {
 		snd_printk(KERN_ERR "%s(): unable to find clock source (clock %d)\n",
@@ -391,7 +390,7 @@
 		break;
 	case UAC_VERSION_2:
 		/* fp->channels is already set in this case */
-		ret = parse_audio_format_rates_v2(chip, fp, iface);
+		ret = parse_audio_format_rates_v2(chip, fp);
 		break;
 	}
 
@@ -450,7 +449,7 @@
 		framesize = le16_to_cpu(fmt->wSamplesPerFrame);
 		snd_printd(KERN_INFO "found format II with max.bitrate = %d, frame size=%d\n", brate, framesize);
 		fp->frame_size = framesize;
-		ret = parse_audio_format_rates_v2(chip, fp, iface);
+		ret = parse_audio_format_rates_v2(chip, fp);
 		break;
 	}
 	}