mtd: rawnand: sunxi: Use struct_size()

Use struct_size() to calculate sunxi_nand object size.
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/raw/sunxi_nand.c

@@ -1871,9 +1871,7 @@ static int sunxi_nand_chip_init(struct device *dev, struct sunxi_nfc *nfc,
 		return -EINVAL;
 	}
 
-	sunxi_nand = devm_kzalloc(dev,
-				  sizeof(*sunxi_nand) +
-				  (nsels * sizeof(struct sunxi_nand_chip_sel)),
+	sunxi_nand = devm_kzalloc(dev, struct_size(sunxi_nand, sels, nsels),
 				  GFP_KERNEL);
 	if (!sunxi_nand) {
 		dev_err(dev, "could not allocate chip\n");