The cyw43-driver uses `printf` by default for `CYW43_PRINTF`, but on the
rp2 port `printf` only goes to a UART output and not to USB CDC.
By defining `CYW43_PRINTF` to `mp_printf`, all the messages from the
cyw43-driver are seen on USB CDC.
For example this allows `network.WLAN().config(trace=1)` to show async
WALN events.
Signed-off-by: Damien George <damien@micropython.org>
ca6723b144