[ALSA] Remove unused variable

USB USX2Y
Removed an unused variable to fix a compile warning.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/usx2y/usbusx2yaudio.c

@@ -415,7 +415,6 @@ static int usX2Y_urbs_allocate(snd_usX2Y_substream_t *subs)
 	unsigned int pipe;
 	int is_playback = subs == subs->usX2Y->subs[SNDRV_PCM_STREAM_PLAYBACK];
 	struct usb_device *dev = subs->usX2Y->chip.dev;
-	struct usb_host_endpoint *ep;
 
 	pipe = is_playback ? usb_sndisocpipe(dev, subs->endpoint) :
 			usb_rcvisocpipe(dev, subs->endpoint);