The pogo keyboard is a USB HID device behind the GL610 hub on
usb@11200000. Enable the USB stack (USB, DM_USB, USB_XHCI_HCD,
USB_XHCI_MTK, USB_STORAGE, CMD_USB), the MTK T-PHY (PHY_MTK_TPHY),
USB_KEYBOARD and CONFIG_USE_PREBOOT (preboot defaults to "usb start"
with USB_KEYBOARD) so the bus is enumerated before the prompt.
The upstream mt8183.dtsi models the SSUSB block for the Linux mtu3
dual-role driver: the IPPC register space and the phys live on the
parent mtu3 node while the xhci child has only its "mac" register.
U-Boot binds the "mediatek,mtk-xhci" child directly and expects
mac+ippc and a phys list on that node, so add a board
-u-boot.dtsi overlay (auto-included after the upstream dts) that
supplies them. No upstream DT files are modified.
stdin=serial,usbkbd routes the prompt through the USB keyboard once
the usb_kbd stdio device is registered.