phy: qcom-qmp: fix return value check in qcom_qmp_phy_create()

In case of error, the function of_iomap() returns NULL pointer
not ERR_PTR(). The IS_ERR() test in the return value check should
be replaced with NULL test.

Fixes: e78f3d15e115 ("phy: qcom-qmp: new qmp phy driver for qcom-chipsets")
Reviewed-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/phy-qcom-qmp.c

@@ -983,16 +983,16 @@ int qcom_qmp_phy_create(struct device *dev, struct device_node *np, int id)
 	 * Resources are indexed as: tx -> 0; rx -> 1; pcs -> 2.
 	 */
 	qphy->tx = of_iomap(np, 0);
-	if (IS_ERR(qphy->tx))
-		return PTR_ERR(qphy->tx);
+	if (!qphy->tx)
+		return -ENOMEM;
 
 	qphy->rx = of_iomap(np, 1);
-	if (IS_ERR(qphy->rx))
-		return PTR_ERR(qphy->rx);
+	if (!qphy->rx)
+		return -ENOMEM;
 
 	qphy->pcs = of_iomap(np, 2);
-	if (IS_ERR(qphy->pcs))
-		return PTR_ERR(qphy->pcs);
+	if (!qphy->pcs)
+		return -ENOMEM;
 
 	/*
 	 * Get PHY's Pipe clock, if any. USB3 and PCIe are PIPE3