mfd: davinci_voicecodec: Fix possible null-ptr-deref davinci_vc_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: b5e29aa ("mfd: davinci_voicecodec: Remove pointless #include")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220426030857.3539336-1-yangyingliang@huawei.com

Author: Yang Yingliang

drivers/mfd/davinci_voicecodec.c

@@ -46,14 +46,12 @@ static int __init davinci_vc_probe(struct platform_device *pdev)
 	}
 	clk_enable(davinci_vc->clk);
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-
-	fifo_base = (dma_addr_t)res->start;
-	davinci_vc->base = devm_ioremap_resource(&pdev->dev, res);
+	davinci_vc->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
 	if (IS_ERR(davinci_vc->base)) {
 		ret = PTR_ERR(davinci_vc->base);
 		goto fail;
 	}
+	fifo_base = (dma_addr_t)res->start;
 
 	davinci_vc->regmap = devm_regmap_init_mmio(&pdev->dev,
 						   davinci_vc->base,