usb: phy: tegra: Use DT helpers for phy_type

Use the new of_usb_get_phy_mode helper function for parsing phy_type
from the device tree.
Signed-off-by: Tuomas Tynkkynen <ttynkkynen@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/phy/phy-tegra-usb.c

@@ -31,6 +31,7 @@
 #include <linux/of_gpio.h>
 #include <linux/usb/otg.h>
 #include <linux/usb/ulpi.h>
+#include <linux/usb/of.h>
 #include <asm/mach-types.h>
 #include <linux/usb/ehci_def.h>
 #include <linux/usb/tegra_usb_phy.h>
@@ -860,6 +861,7 @@ static int tegra_usb_phy_probe(struct platform_device *pdev)
 	struct resource *res;
 	struct tegra_usb_phy *tegra_phy = NULL;
 	struct device_node *np = pdev->dev.of_node;
+	enum usb_phy_interface phy_type;
 	int err;
 
 	tegra_phy = devm_kzalloc(&pdev->dev, sizeof(*tegra_phy), GFP_KERNEL);
@@ -884,12 +886,12 @@ static int tegra_usb_phy_probe(struct platform_device *pdev)
 	tegra_phy->is_legacy_phy =
 		of_property_read_bool(np, "nvidia,has-legacy-mode");
 
-	err = of_property_match_string(np, "phy_type", "ulpi");
-	if (err < 0) {
+	phy_type = of_usb_get_phy_mode(np);
+	if (phy_type == USBPHY_INTERFACE_MODE_UTMI) {
 		err = utmi_phy_probe(tegra_phy, pdev);
 		if (err < 0)
 			return err;
-	} else {
+	} else if (phy_type == USBPHY_INTERFACE_MODE_ULPI) {
 		tegra_phy->is_ulpi_phy = true;
 
 		tegra_phy->reset_gpio =
@@ -899,8 +901,10 @@ static int tegra_usb_phy_probe(struct platform_device *pdev)
 				tegra_phy->reset_gpio);
 			return tegra_phy->reset_gpio;
 		}
-
 		tegra_phy->config = NULL;
+	} else {
+		dev_err(&pdev->dev, "phy_type is invalid or unsupported\n");
+		return -EINVAL;
 	}
 
 	err = of_property_match_string(np, "dr_mode", "otg");