ARM: dts: STiH407-family: set snps,dis_u3_susphy_quirk

Since v4.10-rc1, the following logs appears in loop :
[  801.953836] usb usb6-port1: Cannot enable. Maybe the USB cable is bad?
[  801.960455] xhci-hcd xhci-hcd.0.auto: Cannot set link state.
[  801.966611] usb usb6-port1: cannot disable (err = -32)
[  806.083772] usb usb6-port1: Cannot enable. Maybe the USB cable is bad?
[  806.090370] xhci-hcd xhci-hcd.0.auto: Cannot set link state.
[  806.096494] usb usb6-port1: cannot disable (err = -32)

After analysis, xhci try to set link in U3 and returns an error.
Using snps,dis_u3_susphy_quirk fix this issue.
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>

arch/arm/boot/dts/stih407-family.dtsi

@@ -680,6 +680,7 @@ dwc3: dwc3@9900000 {
 				phy-names	= "usb2-phy", "usb3-phy";
 				phys		= <&usb2_picophy0>,
 						  <&phy_port2 PHY_TYPE_USB3>;
+				snps,dis_u3_susphy_quirk;
 			};
 		};