[PATCH] audio, set urb->interval

This sets urb->interval in two places it hadn't previously been set,
allowing things like SOX and XMMS to play through usb audio.

Using this and the previous patches, I was able to verify playback
of some Ogg Vorbis encoded music using most of the 2.5.17 host
controller drivers.  However, "uhci-hcd" and "usb-uhci-hcd" did
not want to bind the audio driver:  reading the config descriptor
(in audio.c) stalled rather consistently.  That failure was seen
with the other USB 1.1 drivers too, but not as consistently.

drivers/usb/class/audio.c

@@ -1221,6 +1221,7 @@ static int usbout_prepare_desc(struct usbout *u, struct urb *urb)
 		offs += cnt;
 		cp += cnt;
 	}
+	urb->interval = 1;
 	if (err)
 		u->dma.error++;
 	if (u->dma.mapped) {
@@ -1291,6 +1292,7 @@ static int usbout_sync_prepare_desc(struct usbout *u, struct urb *urb)
 		urb->iso_frame_desc[i].length = 3;
 		urb->iso_frame_desc[i].offset = offs;
 	}
+	urb->interval = 1;
 	return 0;
 }