can: peak_usb: convert to use le32_add_cpu()

Convert cpu_to_le32(le32_to_cpu(E1) + E2) to use le32_add_cpu().
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Link: https://lore.kernel.org/r/20200914041744.3701840-1-liushixin2@huawei.comSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

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

@@ -186,7 +186,7 @@ static int pcan_msg_add_rec(struct pcan_usb_pro_msg *pm, int id, ...)
 
 	len = pc - pm->rec_ptr;
 	if (len > 0) {
-		*pm->u.rec_cnt = cpu_to_le32(le32_to_cpu(*pm->u.rec_cnt) + 1);
+		le32_add_cpu(pm->u.rec_cnt, 1);
 		*pm->rec_ptr = id;
 
 		pm->rec_ptr = pc;