Allow TMC baud rate override (#15773)

Marlin/src/module/stepper/trinamic.cpp

Marlin/src/pins/lpc1768/pins_BIGTREE_SKR_V1.3.h

Marlin/src/pins/lpc1768/pins_GMARSH_X6_REV1.h

Marlin/src/pins/lpc1768/pins_MKS_SBASE.h

Marlin/src/pins/lpc1768/pins_MKS_SGEN_L.h

Marlin/src/pins/lpc1768/pins_RAMPS_RE_ARM.h

Marlin/src/pins/lpc1769/pins_MKS_SGEN.h

Marlin/src/pins/lpc1769/pins_TH3D_EZBOARD.h

Marlin/src/pins/stm32/pins_BIGTREE_BTT002_V1.0.h

Marlin/src/pins/stm32/pins_BIGTREE_SKR_E3_DIP.h

Marlin/src/pins/stm32/pins_BIGTREE_SKR_PRO_V1.1.h

Marlin/src/pins/stm32/pins_BTT_SKR_MINI_E3_V1_2.h

Marlin/src/pins/stm32/pins_FYSETC_CHEETAH_V12.h