ALSA: usb: scarless_gen2: fix endianness issue

Fix Sparse warning:

sound/usb/mixer_scarlett_gen2.c:1949:24: warning: cast to restricted
__le32
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200902212133.30964-13-pierre-louis.bossart@linux.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/mixer_scarlett_gen2.c

@@ -1946,7 +1946,7 @@ static void scarlett2_mixer_interrupt(struct urb *urb)
 		goto requeue;
 
 	if (len == 8) {
-		data = le32_to_cpu(*(u32 *)urb->transfer_buffer);
+		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)