spi: rb4xx: use devm_platform_ioremap_resource() to simplify code

Use devm_platform_ioremap_resource() to simplify the code a bit.
This is detected by coccinelle.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20190904135918.25352-25-yuehaibing@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-rb4xx.c

@@ -135,12 +135,10 @@ static int rb4xx_spi_probe(struct platform_device *pdev)
 	struct spi_master *master;
 	struct clk *ahb_clk;
 	struct rb4xx_spi *rbspi;
-	struct resource *r;
 	int err;
 	void __iomem *spi_base;
 
-	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	spi_base = devm_ioremap_resource(&pdev->dev, r);
+	spi_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(spi_base))
 		return PTR_ERR(spi_base);