Previously, setting MICROPY_HW_ENABLE_USBDEV to 0 caused build errors. The
change affects the nrf and samd ports as well, so MICROPY_HW_ENABLE_USBDEV
had to be explicitly enabled there.
The configuration options MICROPY_HW_ENABLE_USBDEV and
MICROPY_HW_ENABLE_UART_REPL are independent, and can be enabled or disabled
by a board.
Signed-off-by: Damien George <damien@micropython.org>