ARM: DT: STi: STiH418: Enable USB3 port on stih418-b2199.

The USB3 controller is present on the b2199 board, so enable
it in the board specific DT file.
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>

arch/arm/boot/dts/stih418-b2199.dts

@@ -97,5 +97,9 @@ phy_port1: port@9b2a000 {
 				st,osc-force-ext;
 			};
 		};
+
+		st_dwc3: dwc3@8f94000 {
+			status = "okay";
+		};
 	};
 };