can: peak_usb: pcan_usb_get_serial(): make use of le32_to_cpup()

This patch replaces the memcpy() + le32_to_cpu() by le32_to_cpup().

Link: https://lore.kernel.org/r/20210406111622.1874957-9-mkl@pengutronix.deAcked-by: Stephane Grosjean <s.grosjean@peak-system.com>
Tested-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/peak_usb/pcan_usb.c

@@ -368,12 +368,8 @@ static int pcan_usb_get_serial(struct peak_usb_device *dev, u32 *serial_number)
 	if (err)
 		return err;
 
-	if (serial_number) {
-		__le32 tmp32;
-
-		memcpy(&tmp32, args, 4);
-		*serial_number = le32_to_cpu(tmp32);
-	}
+	if (serial_number)
+		*serial_number = le32_to_cpup((__le32 *)args);
 
 	return 0;
 }