phy: armada375-usb2: Set drvdata for phy and use it

At the context we have pointer to struct phy, it's useful to call
phy_get_drvdata() to get the address of cluster_phy. This has slightly
better readability than calling dev_get_drvdata(phy->dev.parent).

Signed-off-by: Axel Lin <[e-mail]>
Signed-off-by: Kishon Vijay Abraham I <[e-mail]>

drivers/phy/phy-armada375-usb2.c

···
 	struct armada375_cluster_phy *cluster_phy;
 	u32 reg;
 
-	cluster_phy = dev_get_drvdata(phy->dev.parent);
+	cluster_phy = phy_get_drvdata(phy);
 	if (!cluster_phy)
 		return -ENODEV;
 
···
 	cluster_phy->reg = usb_cluster_base;
 
 	dev_set_drvdata(dev, cluster_phy);
+	phy_set_drvdata(phy, cluster_phy);
 
 	phy_provider = devm_of_phy_provider_register(&pdev->dev,
 						     armada375_usb_phy_xlate);