[ALSA] usb-audio - remove superfluous parameter

USB generic driver,USB USX2Y
This patch removes the superfluous driver parameter from the
disconnect functions.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index eecbf19..14f7cf7 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -223,7 +223,7 @@
 int snd_usb_create_midi_interface(snd_usb_audio_t *chip, struct usb_interface *iface, const snd_usb_audio_quirk_t *quirk);
 void snd_usbmidi_input_stop(struct list_head* p);
 void snd_usbmidi_input_start(struct list_head* p);
-void snd_usbmidi_disconnect(struct list_head *p, struct usb_driver *driver);
+void snd_usbmidi_disconnect(struct list_head *p);
 
 /*
  * retrieve usb_interface descriptor from the host interface