This fixes compilation issues in `tests/pkg/tinyusb_netdev` with
newer versions of the RISC-V toolchain due to two competing USB
stacks being pulled in. With the older toolchain the build system
warns:
The following features may conflict: periph_usbdev tinyusb_device
But builds fine (even though surprises at runtime are likely). The
newer toolchain takes an issue with the same symbol being linked
in more than once (and more than one instance not being `weak`).
After a reset, it can take several seconds before the CDC ACM interface becomes available as serial device `ttyACMx`. This was a change that was already made for `stdio_cdc_acm` in #19128.
