DM scans only the immediate subnodes of a bound node; recursion into
children happens when a bound bus driver runs dm_scan_fdt_dev. Nothing
in U-Boot binds the "mediatek,mtu3" ssusb@11201000 node, so its xhci
child (usb@11200000) was never bound, no UCLASS_USB device existed and
usb start() reported "No USB controllers found".
Add "simple-mfd" to the ssusb compatible in the -u-boot.dtsi overlay
so the generic simple-bus driver binds the node and scans its children.
vhaudiquet
75fe5bc9de