ALSA: line6: Use kmemdup in podhd_set_monitor_level()

Use kmemdup rather than duplicating its implementation.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20200717081710.39180-1-yuehaibing@huawei.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/line6/podhd.c

@@ -293,12 +293,10 @@ static void podhd_set_monitor_level(struct usb_line6_podhd *podhd, int value)
 	};
 	unsigned char *buf;
 
-	buf = kmalloc(sizeof(msg), GFP_KERNEL);
+	buf = kmemdup(msg, sizeof(msg), GFP_KERNEL);
 	if (!buf)
 		return;
 
-	memcpy(buf, msg, sizeof(msg));
-
 	if (value < 0)
 		value = 0;