phy: phy-rockchip-inno-usb2: support standalone phy nodes

New Rockchip devices have the usb2 phy devices as standalone nodes
instead of children of the grf node.
Allow the driver to find the grf node from a phandle.
Signed-off-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Michael Riesch <michael.riesch@wolfvision.net>
Link: https://lore.kernel.org/r/20211215210252.120923-5-pgwipeout@gmail.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/rockchip/phy-rockchip-inno-usb2.c

@@ -1073,12 +1073,19 @@ static int rockchip_usb2phy_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	if (!dev->parent || !dev->parent->of_node)
-		return -EINVAL;
+	if (!dev->parent || !dev->parent->of_node) {
+		rphy->grf = syscon_regmap_lookup_by_phandle(np, "rockchip,usbgrf");
+		if (IS_ERR(rphy->grf)) {
+			dev_err(dev, "failed to locate usbgrf\n");
+			return PTR_ERR(rphy->grf);
+		}
+	}
 
-	rphy->grf = syscon_node_to_regmap(dev->parent->of_node);
-	if (IS_ERR(rphy->grf))
-		return PTR_ERR(rphy->grf);
+	else {
+		rphy->grf = syscon_node_to_regmap(dev->parent->of_node);
+			if (IS_ERR(rphy->grf))
+				return PTR_ERR(rphy->grf);
+	}
 
 	if (of_device_is_compatible(np, "rockchip,rv1108-usb2phy")) {
 		rphy->usbgrf =