irqchip/qcom-mpm: Fix IS_ERR() vs NULL check in qcom_mpm_init()

devm_ioremap() doesn't return error pointers, it returns NULL on error.
Update the check accordingly.

Fixes: 221b110d ("irqchip/qcom-mpm: Support passing a slice of SRAM as reg space")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/22e1f4de-edce-4791-bd2d-2b2e98529492@moroto.mountain

drivers/irqchip/irq-qcom-mpm.c

@@ -389,8 +389,8 @@ static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
 		/* Don't use devm_ioremap_resource, as we're accessing a shared region. */
 		priv->base = devm_ioremap(dev, res.start, resource_size(&res));
 		of_node_put(msgram_np);
-		if (IS_ERR(priv->base))
-			return PTR_ERR(priv->base);
+		if (!priv->base)
+			return -ENOMEM;
 	} else {
 		/* Otherwise, fall back to simple MMIO. */
 		priv->base = devm_platform_ioremap_resource(pdev, 0);