Launch and ros2 run fails a libusb assert when no usb gps device initially attached

[hortovanyi]

libusb appears to be attempting to transmit to USB devices upon startup.

There is an Assert checking that the devHandle is not null in the libusb library.

Need to investigate:
1/ if this is relating to the hot_plug enumeration on startup;
2/ that we need to do a more simple check during ublox_dgnss_node initialisation for if at least one Ublox f9 type gps device is attached;or
3/ a bug with libusb