ALSA: usb-audio: scarlett_gen2: Fix another -Wformat-truncation warning

The recent enablement of -Wformat-truncation leads to a false-positive
warning for mixer_scarlett_gen2.c.

For suppressing the warning, replace snprintf() with scnprintf().
As stated in the above, truncation doesn't matter.

Fixes: 78bd8f51 ("ALSA: usb-audio: scarlett_gen2: Fix -Wformat-truncation warning")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20230919071205.10684-1-peter.ujfalusi@linux.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/mixer_scarlett_gen2.c

@@ -3205,8 +3205,8 @@ static int scarlett2_add_line_in_ctls(struct usb_mixer_interface *mixer)
 	/* Add input phantom controls */
 	if (info->inputs_per_phantom == 1) {
 		for (i = 0; i < info->phantom_count; i++) {
-			snprintf(s, sizeof(s), fmt, i + 1,
-				 "Phantom Power", "Switch");
+			scnprintf(s, sizeof(s), fmt, i + 1,
+				  "Phantom Power", "Switch");
 			err = scarlett2_add_new_ctl(
 				mixer, &scarlett2_phantom_ctl,
 				i, 1, s, &private->phantom_ctls[i]);