usb: Skeleton platform code for FTDI FT4222 USB to i2c bridge

Signed-off-by: Henry Bruce <henry.bruce@intel.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

include/mraa_internal.h

@@ -59,6 +59,13 @@ mraa_platform_t mraa_x86_platform();
  */
 mraa_platform_t mraa_arm_platform();
 
+/**
+ * runtime detect running usb platform extender
+ *
+ * @return mraa_platform_t of the detected platform extender
+ */
+mraa_platform_t mraa_usb_platform_extender(mraa_board_t* board);
+
 /**
  * helper function to check if file exists
  *