Update flash_api.c

mbed_critical.h replaced with "platform/mbed_critical.h" (to match template)
typo corrected

Author: 0x6d61726b

targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F439xI/device/flash_api.c

@@ -16,9 +16,9 @@
 
 #include "flash_api.h"
 #include "flash_data.h"
-#include "mbed_critical.h"
+#include "platform/mbed_critical.h"
 
-// This file is automagically generated
+// This file is automatically generated
 
 #if DEVICE_FLASH