net: dsa: rzn1-a5psw: fix a NULL vs IS_ERR() check in a5psw_probe()

The devm_platform_ioremap_resource() function never returns NULL.
It returns error pointers.
Signed-off-by: Peng Wu <wupeng58@huawei.com>
Reported-by: Hulk Robot <hulkci@huawei.com>
Reviewed-by: Clément Léger <clement.leger@bootlin.com>
Link: https://lore.kernel.org/r/20220628130920.49493-1-wupeng58@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/rzn1_a5psw.c

@@ -946,8 +946,8 @@ static int a5psw_probe(struct platform_device *pdev)
 	mutex_init(&a5psw->lk_lock);
 	spin_lock_init(&a5psw->reg_lock);
 	a5psw->base = devm_platform_ioremap_resource(pdev, 0);
-	if (!a5psw->base)
-		return -EINVAL;
+	if (IS_ERR(a5psw->base))
+		return PTR_ERR(a5psw->base);
 
 	ret = a5psw_pcs_get(a5psw);
 	if (ret)