ALSA: usb-audio: scarlett2: Remove interrupt debug message

Just ignore instead of printing an error if the interrupt data is not
the expected length. This check was for development and the condition
has not been observed.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/20210620164632.GA9186@m.b4.vu
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/mixer_scarlett_gen2.c

@@ -2018,19 +2018,14 @@ static void scarlett2_mixer_interrupt(struct urb *urb)
 	int ustatus = urb->status;
 	u32 data;
 
-	if (ustatus != 0)
+	if (ustatus != 0 || len != 8)
 		goto requeue;
 
-	if (len == 8) {
 	data = le32_to_cpu(*(__le32 *)urb->transfer_buffer);
 	if (data & SCARLETT2_USB_INTERRUPT_VOL_CHANGE)
 		scarlett2_mixer_interrupt_vol_change(mixer);
 	if (data & SCARLETT2_USB_INTERRUPT_BUTTON_CHANGE)
 		scarlett2_mixer_interrupt_button_change(mixer);
-	} else {
-		usb_audio_err(mixer->chip,
-			      "scarlett mixer interrupt length %d\n", len);
-	}
 
 requeue:
 	if (ustatus != -ENOENT &&