Fixed common_hal_busio_uart_deinited incorrect pin assignment check.

[EmergReanimator]

The pin must be tested instead of pin->number in the same way as in STM
I2C busio layer.

 pytest -s -v test_busio.py --port=/dev/ttyACM2 --html-report=./report/stm32_f4ve.html
============================================================================================================ test session starts =============================================================================================================
platform linux -- Python 3.10.1, pytest-6.2.4, py-1.11.0, pluggy-0.13.1 -- /usr/bin/python3
cachedir: .pytest_cache
rootdir: /work/external/repos/circuitpython/tests/circuitpython-r
[report-stm32_f4ve.zip](https://github.com/adafruit/circuitpython/files/7964098/report-stm32_f4ve.zip)
egression
plugins: html-reporter-0.2.6
collected 6 items                                                                                                                                                                                                                            

test_busio.py::Test_SPI::test_SPI PASSED
test_busio.py::Test_SPI::test_configure PASSED
test_busio.py::Test_SPI::test_frequency PASSED
test_busio.py::Test_SPI::test_try_lock PASSED
test_busio.py::Test_SPI::test_unlock PASSED
test_busio.py::Test_SPI::test_write PASSED

============================================================================================================= 6 passed in 3.78s ==============================================================================================================

[dhalbert]

Thanks for catching this!