Fix backlight for F401/F411 blackpill onekey examples (#10320)
Fix configs to make the `handwired/onekey/blackpill_f401:backlight` and
`handwired/onekey/blackpill_f411:backlight` examples actually compile
and work:
- Use `PWMD5` instead of `PWMD2` for backlight, which matches the
default value of `BACKLIGHT_PAL_MODE` (AF02 for pin A0 is `TIM5_CH1`)
and does not conflict with the default value of `STM32_ST_USE_TIMER`.
- Enable `HAL_USE_PWM` in halconf.h and `STM32_PWM_USE_TIM5` in
mcuconf.h, so that `PWMD5` could be used.