Boards classification arrangement (#10814)

STM32 ARM Cortex-M3 boards were listed as M4

Marlin/src/core/boards.h

 #define BOARD_ALLIGATOR        1602   // Alligator Board R2
 
 //
-// ARM Cortex M4
+// STM32 ARM Cortex-M3
 //
-#define BOARD_TEENSY35_36       841   // Teensy3.5 and Teensy3.6
 #define BOARD_STM32F1R         1800   // STM3R Libmaple based STM32F1 controller
 #define BOARD_MALYAN_M200      1801   // STM32C8T6 Libmaple based stm32f1 controller
-#define BOARD_BEAST            1802   // STM32FxxxVxT6 Libmaple based stm32f4 controller
 #define BOARD_STM3R_MINI       1803   // STM32 Libmaple based stm32f1 controller
+
+//
+// STM32 ARM Cortex-M4F
+//
+#define BOARD_TEENSY35_36       841   // Teensy3.5 and Teensy3.6
+#define BOARD_BEAST            1802   // STM32FxxxVxT6 Libmaple based stm32f4 controller
 #define BOARD_STM32F4          1804   // STM32 STM32GENERIC based STM32F4 controller
 
 //