ALSA: usb-audio: replace hardcoded value with const

In this context, 0x01 is USB_ENDPOINT_XFER_ISOC.
Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/pcm.c

@@ -384,7 +384,7 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 		/* ... and check descriptor size before accessing bSynchAddress
 		   because there is a version of the SB Audigy 2 NX firmware lacking
 		   the audio fields in the endpoint descriptors */
-		if ((get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != 0x01 ||
+		if ((get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != USB_ENDPOINT_XFER_ISOC ||
 		    (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
 		     get_endpoint(alts, 1)->bSynchAddress != 0 &&
 		     !implicit_fb)) {