[Generic F401Rx] Fix clock settings

Signed-off-by: Frederic Pillon <[email protected]>

Author: fpistm

variants/Generic_F401Rx/variant.cpp

@@ -143,7 +143,7 @@ static uint8_t SetSysClock_PLL_HSE(uint8_t bypass)
 
   RCC_OscInitStruct.PLL.PLLState        = RCC_PLL_ON;
   RCC_OscInitStruct.PLL.PLLSource       = RCC_PLLSOURCE_HSE;
-  RCC_OscInitStruct.PLL.PLLM            = 8;             // VCO input clock = 1 MHz (8 MHz / 8)
+  RCC_OscInitStruct.PLL.PLLM            = HSE_VALUE / 1000000L; // Expects an 8 MHz external clock by default. Redefine HSE_VALUE if not
   RCC_OscInitStruct.PLL.PLLN            = 336;           // VCO output clock = 336 MHz (1 MHz * 336)
   RCC_OscInitStruct.PLL.PLLP            = RCC_PLLP_DIV4; // PLLCLK = 84 MHz (336 MHz / 4)
   RCC_OscInitStruct.PLL.PLLQ            = 7;             // USB clock = 48 MHz (336 MHz / 7) --> OK for USB