dts: fix RT-AC58U to match the updated device tree name/alias changes.

A variety of subtle changes occured with the upstream syncs over time.

This allows the RT-AC58U to boot and have working USB3.

Locally tested:

* Asus RT-AC58U, USB3 (umass)

Differential Revision:	https://reviews.freebsd.org/D49685
Reviewed by:	manu

sys/dts/arm/qcom-ipq4018-rt-ac58u.dts

@@ -67,10 +67,10 @@
 			qcom,wifi_noc_memtype_m0_m2 = <TCSR_WIFI_NOC_MEMTYPE_M0_M2>;
 		};
 
-		usb3@8af8800 {
+		usb@8af8800 {
 			status = "okay";
 
-			dwc3@8a00000 {
+			usb@8a00000 {
 				#address-cells = <1>;
 				#size-cells = <0>;