Allow STM32 HAL_TIMER_RATE override (#18374)

Marlin/src/HAL/STM32/timers.cpp

 #endif
 
 #ifdef STM32F0xx
-  #define HAL_TIMER_RATE (F_CPU)      // Frequency of timer peripherals
+  #define MCU_TIMER_RATE (F_CPU)      // Frequency of timer peripherals
   #define MCU_STEP_TIMER 16
   #define MCU_TEMP_TIMER 17
 #elif defined(STM32F1xx)
-  #define HAL_TIMER_RATE (F_CPU)
+  #define MCU_TIMER_RATE (F_CPU)
   #define MCU_STEP_TIMER  4
   #define MCU_TEMP_TIMER  2
 #elif defined(STM32F401xC) || defined(STM32F401xE)
-  #define HAL_TIMER_RATE (F_CPU / 2)
+  #define MCU_TIMER_RATE (F_CPU / 2)
   #define MCU_STEP_TIMER  9
   #define MCU_TEMP_TIMER 10
 #elif defined(STM32F4xx) || defined(STM32F7xx)
-  #define HAL_TIMER_RATE (F_CPU / 2)
+  #define MCU_TIMER_RATE (F_CPU / 2)
   #define MCU_STEP_TIMER  6           // STM32F401 has no TIM6, TIM7, or TIM8
   #define MCU_TEMP_TIMER 14           // TIM7 is consumed by Software Serial if used.
 #endif
 
+#ifndef HAL_TIMER_RATE
+  #define HAL_TIMER_RATE MCU_TIMER_RATE
+#endif
 #ifndef STEP_TIMER
   #define STEP_TIMER MCU_STEP_TIMER
 #endif

Marlin/src/pins/stm32f4/pins_RUMBA32_common.h

 #define STEP_TIMER                          10
 #define TEMP_TIMER                          14
 #define TIMER_SERIAL                        TIM9
+#define HAL_TIMER_RATE                      F_CPU
 
 //
 // Limit Switches