stm32/mpbthciport: Fix initial baudrate to use provided value.
stm32/mpbthciport: Fix initial baudrate to use provided value.

Fixes bug introduced in the recent bffb71f523e4bcc21b913af291deeb67091bed88

henriknelson/micropython,adafruit/circuitpython,adafruit/circuitpython,bvernoux/micropython,henriknelson/micropython,bvernoux/micropython,bvernoux/micropython,adafruit/circuitpython,henriknelson/micropython,adafruit/circuitpython,henriknelson/micropython,adafruit/circuitpython,bvernoux/micropython,henriknelson/micropython,bvernoux/micropython,adafruit/circuitpython