Add new LPC include folder

Marlin/src/HAL/HAL_LPC1768/include/SoftwareSerial.cpp

@@ -42,7 +42,7 @@
 #include <stdarg.h>
 #include <Arduino.h>
 #include <pinmapping.h>
-#include "fastio.h"
+#include "../fastio.h"
 #include "SoftwareSerial.h"
 
 void GpioEnableInt(uint32_t port, uint32_t pin, uint32_t mode);