boards: add zephyr_udc0 nodelabel to all boards with USB support

USB devicetree nodes in Zephyr have different names,
mostly derived from the designations in data sheets.
Add zephyr_udc0 (USB device controller) nodelabel to
specific USB node to allow generic USB sample to be build.

Follow up on commit b4242a8d ("boards: add USB node aliases")

Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>