linux/usb/audio.h: split header

- Split the audio.h file in two to clearly denote the differences
  between the standards.
- Add many more defines to audio-v2.h. Most of them are not currently
  used.
- Replaced a magic value with a proper define

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/card.c

@@ -45,6 +45,7 @@
 #include <linux/moduleparam.h>
 #include <linux/mutex.h>
 #include <linux/usb/audio.h>
+#include <linux/usb/audio-v2.h>
 
 #include <sound/core.h>
 #include <sound/info.h>
@@ -250,7 +251,7 @@ static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
 		 * clock selectors and sample rate conversion units. */
 
 		cs = snd_usb_find_csint_desc(host_iface->extra, host_iface->extralen,
-						NULL, UAC_CLOCK_SOURCE);
+						NULL, UAC2_CLOCK_SOURCE);
 
 		if (!cs) {
 			snd_printk(KERN_ERR "CLOCK_SOURCE descriptor not found\n");