usb: gadget: function: uac2: prevent double ep disable

without this check, f_uac2 would try to disable
the same endpoint twice. Fix that.
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/function/f_uac2.c

@@ -951,6 +951,9 @@ free_ep(struct uac2_rtd_params *prm, struct usb_ep *ep)
 	struct snd_uac2_chip *uac2 = prm->uac2;
 	int i;
 
+	if (!prm->ep_enabled)
+		return;
+
 	prm->ep_enabled = false;
 
 	for (i = 0; i < USB_XFERS; i++) {