ARM: dts: stm32: enable USB Host (USBH) EHCI controller on stm32mp15 DKx

This patch enables USB Host (USBH) EHCI controller on stm32mp15 dk boards.
As a hub is used between USBH and USB connectors, no need to enable
USBH OHCI controller: all low- and full-speed traffic is managed by the
hub.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp15xx-dkx.dtsi

@@ -589,6 +589,11 @@ &uart4 {
 	status = "okay";
 };
 
+&usbh_ehci {
+	phys = <&usbphyc_port0>;
+	status = "okay";
+};
+
 &usbphyc {
 	status = "okay";
 };