STM32L4_NUSART was set to 4. The spec at
https://www.st.com/resource/en/datasheet/stm32l433cc.pdf states the
following on page 1:
- 4x USARTs (ISO 7816, LIN, IrDA, modem)
- 1x LPUART (Stop 2 wake-up)
However it on page 49, it states:
The STM32L433xx devices have three embedded universal synchronous
receiver transmitters (USART1, USART2 and USART3).
The latter is correct.
This patch sets STM32L4_NUSART to 3.