irqchip/ls-extirq: Fix devm_of_iomap() error check

The devm_of_iomap() function returns an ERR_PTR() encoded error code on
failure. Replace the incorrect check against NULL with IS_ERR().

Fixes: 05cd654 ("irqchip/ls-extirq: Convert to a platform driver to make it work again")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Herve Codina <herve.codina@bootlin.com>
Link: https://patch.msgid.link/20260224113610.1129022-3-ioana.ciornei@nxp.com
Closes: https://lore.kernel.org/all/aYXvfbfT6w0TMsXS@stanley.mountain/

Author: IoanaCiornei

drivers/irqchip/irq-ls-extirq.c

@@ -190,8 +190,10 @@ static int ls_extirq_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, -ENOMEM, "Failed to allocate memory\n");
 
 	priv->intpcr = devm_of_iomap(dev, node, 0, NULL);
-	if (!priv->intpcr)
-		return dev_err_probe(dev, -ENOMEM, "Cannot ioremap OF node %pOF\n", node);
+	if (IS_ERR(priv->intpcr)) {
+		return dev_err_probe(dev, PTR_ERR(priv->intpcr),
+				     "Cannot ioremap OF node %pOF\n", node);
+	}
 
 	ret = ls_extirq_parse_map(priv, node);
 	if (ret)