phy: qcom-qusb2: get optional clock by devm_clk_get_optional()

Use devm_clk_get_optional() to get optional clock

Cc: Andy Gross <andy.gross@linaro.org>
Cc: David Brown <david.brown@linaro.org>
Cc: Vivek Gautam <vivek.gautam@codeaurora.org>
Signed-off-by: NChunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: NKishon Vijay Abraham I <kishon@ti.com>

drivers/phy/qualcomm/phy-qcom-qusb2.c

@@ -822,14 +822,9 @@ static int qusb2_phy_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	qphy->iface_clk = devm_clk_get(dev, "iface");
-	if (IS_ERR(qphy->iface_clk)) {
-		ret = PTR_ERR(qphy->iface_clk);
-		if (ret == -EPROBE_DEFER)
-			return ret;
-		qphy->iface_clk = NULL;
-		dev_dbg(dev, "failed to get iface clk, %d\n", ret);
-	}
+	qphy->iface_clk = devm_clk_get_optional(dev, "iface");
+	if (IS_ERR(qphy->iface_clk))
+		return PTR_ERR(qphy->iface_clk);
 
 	qphy->phy_reset = devm_reset_control_get_by_index(&pdev->dev, 0);
 	if (IS_ERR(qphy->phy_reset)) {