ARM: dts: uniphier: add dr_mode property to dwc3 node

Since commit 576e3cc700c5 ("usb: host: xhci-dwc3: Add dual role mode
support from DT"), warning is displayed if dr_mode is not specified.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/dts/uniphier-pro4.dtsi b/arch/arm/dts/uniphier-pro4.dtsi
index 60287c4..cbb8482 100644
--- a/arch/arm/dts/uniphier-pro4.dtsi
+++ b/arch/arm/dts/uniphier-pro4.dtsi
@@ -587,6 +587,7 @@
 				compatible = "snps,dwc3";
 				reg = <0x65a00000 0x10000>;
 				interrupts = <0 134 4>;
+				dr_mode = "host";
 				tx-fifo-resize;
 			};
 		};
@@ -604,6 +605,7 @@
 				compatible = "snps,dwc3";
 				reg = <0x65c00000 0x10000>;
 				interrupts = <0 137 4>;
+				dr_mode = "host";
 				tx-fifo-resize;
 			};
 		};