mtd: rawnand: cadence: fix possible null-ptr-deref in cadence_nand_dt_probe()

It will cause null-ptr-deref when using 'res', if platform_get_resource()
returns NULL, so move using 'res' after devm_ioremap_resource() that
will check it to avoid null-ptr-deref.
And use devm_platform_get_and_ioremap_resource() to simplify code.

Fixes: ec4ba01e ("mtd: rawnand: Add new Cadence NAND driver to MTD subsystem")
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220426084913.4021868-1-yangyingliang@huawei.com

drivers/mtd/nand/raw/cadence-nand-controller.c

@@ -2983,11 +2983,10 @@ static int cadence_nand_dt_probe(struct platform_device *ofdev)
 	if (IS_ERR(cdns_ctrl->reg))
 		return PTR_ERR(cdns_ctrl->reg);
 
-	res = platform_get_resource(ofdev, IORESOURCE_MEM, 1);
-	cdns_ctrl->io.dma = res->start;
-	cdns_ctrl->io.virt = devm_ioremap_resource(&ofdev->dev, res);
+	cdns_ctrl->io.virt = devm_platform_get_and_ioremap_resource(ofdev, 1, &res);
 	if (IS_ERR(cdns_ctrl->io.virt))
 		return PTR_ERR(cdns_ctrl->io.virt);
+	cdns_ctrl->io.dma = res->start;
 
 	dt->clk = devm_clk_get(cdns_ctrl->dev, "nf_clk");
 	if (IS_ERR(dt->clk))