Allow for overriding clocks on F4xx. (#12886)

platforms/chibios/BLACKPILL_STM32_F401/configs/config.h

@@ -17,8 +17,13 @@
 
 #define BOARD_OTG_NOVBUSSENS 1
 
-#define STM32_LSECLK 32768U
-#define STM32_HSECLK 25000000U
+#ifndef STM32_LSECLK
+#    define STM32_LSECLK 32768U
+#endif  // STM32_LSECLK
+
+#ifndef STM32_HSECLK
+#    define STM32_HSECLK 25000000U
+#endif  // STM32_HSECLK
 
 #ifndef EARLY_INIT_PERFORM_BOOTLOADER_JUMP
 #    define EARLY_INIT_PERFORM_BOOTLOADER_JUMP TRUE

platforms/chibios/BLACKPILL_STM32_F411/configs/config.h

@@ -17,8 +17,13 @@
 
 #define BOARD_OTG_NOVBUSSENS 1
 
-#define STM32_LSECLK 32768U
-#define STM32_HSECLK 25000000U
+#ifndef STM32_LSECLK
+#    define STM32_LSECLK 32768U
+#endif  // STM32_LSECLK
+
+#ifndef STM32_HSECLK
+#    define STM32_HSECLK 25000000U
+#endif  // STM32_HSECLK
 
 #ifndef EARLY_INIT_PERFORM_BOOTLOADER_JUMP
 #    define EARLY_INIT_PERFORM_BOOTLOADER_JUMP TRUE