phy: tegra: xusb: Parse dual-role mode property

The device tree bindings document the "mode" property of "ports"
subnodes, but the driver was not parsing the property. In preparation
for adding role switching, parse the property at probe time.

Based on work by JC Kuo <jckuo@nvidia.com>.

Reviewed-by: JC Kuo <jckuo@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/tegra/xusb.h

@@ -19,6 +19,8 @@
 #include <linux/mutex.h>
 #include <linux/workqueue.h>
 
+#include <linux/usb/otg.h>
+
 /* legacy entry points for backwards-compatibility */
 int tegra_xusb_padctl_legacy_probe(struct platform_device *pdev);
 int tegra_xusb_padctl_legacy_remove(struct platform_device *pdev);
@@ -271,6 +273,7 @@ struct tegra_xusb_usb2_port {
 	struct tegra_xusb_port base;
 
 	struct regulator *supply;
+	enum usb_dr_mode mode;
 	bool internal;
 };