Read STM32 clock rates from framework

[sjasonsmith]

Description

STM32 timer clock rates are not always constant across a device. Depending on the timer they may be F_CPU, F_CPU/2, or maybe even other values (there are lots of STM32 devices, and I haven't read all their datasheets!).

This change reads the timer's clock rate from the framework, rather than assuming Marlin knows the correct value. This makes our code more generic and easier to implement across the wide range of devices that will be supported by the STM32 HAL.

This also removes the ability to override HAL_TIMER_RATE, which was added for the Rumba32. It is simply no longer necessary.

I tested this on an SKR Pro, by moving the STEP timer to TIMER 10, as does the Rumba32. I both reproduced the original "double step rate" issue seen on the Rumba, then verified that this PR fixes it.

Benefits

• Eliminates the need to consider timer clock rate when selecting timer assignments.
• Fixes a babystepping compilation issue, where timers.h depends on a define from timers.cpp.

Configurations

N/A

Related Issues

Fixes: #18961
Replaces former solution for Rumba32: #18374