ata: palmld: fix return value check in palmld_pata_probe()

If devm_platform_ioremap_resource() fails, it never return
NULL pointer, replace the check with IS_ERR().

Fixes: 57bf0f5a16 ("ARM: pxa: use pdev resource for palmld mmio")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

drivers/ata/pata_palmld.c

@@ -63,8 +63,8 @@ static int palmld_pata_probe(struct platform_device *pdev)
 
 	/* remap drive's physical memory address */
 	mem = devm_platform_ioremap_resource(pdev, 0);
-	if (!mem)
-		return -ENOMEM;
+	if (IS_ERR(mem))
+		return PTR_ERR(mem);
 
 	/* request and activate power and reset GPIOs */
 	lda->power = devm_gpiod_get(dev, "power", GPIOD_OUT_HIGH);