HAL_ChibiOS: support 24MHz f3 MCUs

libraries/AP_HAL_ChibiOS/hwdef/common/stm32f3_mcuconf.h

@@ -32,7 +32,7 @@
  * HAL driver system settings.
  */
 #define STM32_NO_INIT                       FALSE
-#define STM32_HSI_ENABLED                   TRUE
+#define STM32_HSI_ENABLED                   FALSE
 #define STM32_LSI_ENABLED                   FALSE
 #define STM32_HSE_ENABLED                   TRUE
 #define STM32_LSE_ENABLED                   FALSE
@@ -46,6 +46,15 @@
 #define STM32_PPRE2                         STM32_PPRE2_DIV2
 #define STM32_ADCPRE                        STM32_ADCPRE_DIV4
 #define STM32_HPRE                          STM32_HPRE_DIV1
+#elif STM32_HSECLK == 24000000U
+#define STM32_SW                            STM32_SW_PLL
+#define STM32_PLLSRC                        STM32_PLLSRC_HSE
+#define STM32_PLLXTPRE                      STM32_PLLXTPRE_DIV1
+#define STM32_PLLMUL_VALUE                  3
+#define STM32_PPRE1                         STM32_PPRE1_DIV2
+#define STM32_PPRE2                         STM32_PPRE2_DIV2
+#define STM32_ADCPRE                        STM32_ADCPRE_DIV4
+#define STM32_HPRE                          STM32_HPRE_DIV1
 #else
 #error "Unsupported STM32F1xx clock frequency"
 #endif