spi: ath79: 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/20190904135918.25352-4-yuehaibing@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-ath79.c

@@ -139,7 +139,6 @@ static int ath79_spi_probe(struct platform_device *pdev)
 	struct spi_master *master;
 	struct ath79_spi *sp;
 	struct ath79_spi_platform_data *pdata;
-	struct resource	*r;
 	unsigned long rate;
 	int ret;
 
@@ -169,8 +168,7 @@ static int ath79_spi_probe(struct platform_device *pdev)
 	sp->bitbang.txrx_word[SPI_MODE_0] = ath79_spi_txrx_mode0;
 	sp->bitbang.flags = SPI_CS_HIGH;
 
-	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	sp->base = devm_ioremap_resource(&pdev->dev, r);
+	sp->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(sp->base)) {
 		ret = PTR_ERR(sp->base);
 		goto err_put_master;