Fix BLTOUCH and FAN PWM conflicts on SKR E3 boards (#15547)

Marlin/src/HAL/HAL_STM32F1/HAL.cpp

Marlin/src/HAL/HAL_STM32F1/timers.cpp

Marlin/src/HAL/HAL_STM32F1/timers.h

Marlin/src/core/boards.h

Marlin/src/feature/digipot/digipot_mcp4451.cpp

Marlin/src/inc/Conditionals_LCD.h

Marlin/src/lcd/dogm/ultralcd_DOGM.h

Marlin/src/lcd/dogm/ultralcd_st7920_u8glib_rrd_AVR.h

Marlin/src/pins/mega/pins_MEGATRONICS_3.h

Marlin/src/pins/pins.h

Marlin/src/pins/sanguino/pins_MELZI.h

Marlin/src/pins/sanguino/pins_SANGUINOLOLU_11.h

buildroot/share/tests/STM32F103RC_bigtree_USB-tests