Merge pull request #9552 from jeromecoutant/PR_H7OS2

STM32H7: Enable OS2 compilation

Author: 0xc0170

targets/TARGET_STM/TARGET_STM32H7/device/Legacy/stm32_hal_legacy.h renamed to targets/TARGET_STM/TARGET_STM32H7/device/stm32_hal_legacy.h

@@ -28,7 +28,7 @@
 
 /* Includes ------------------------------------------------------------------*/
 #include "stm32h7xx.h"
-#include "Legacy/stm32_hal_legacy.h"
+#include "stm32_hal_legacy.h"
 #include <stddef.h>
 #include <math.h>