arm64: dts: verdin-imx8mp: dahlia: mark usb_2 permanently attached

As both Dahlia and the Verdin Development Board have on-carrier
permanently attached USB hubs mark Verdin USB_2 as such.
Signed-off-by: NMarcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mp-verdin-dahlia.dtsi

@@ -116,6 +116,7 @@
 
 /* Verdin USB_2 */
 &usb3_1 {
+	fsl,permanently-attached;
 	status = "okay";
 };