LED display internal API
  =======================================
  
  This README describes the LED display API.
  
  The API is defined by the include file include/led-display.h
  
  The first step in to define CONFIG_CMD_DISPLAY in the board config file.
  Then you need to provide the following functions to access LED display:
  
  void display_set(int cmd);
  
  This function should control the state of the LED display. Argument is
  an ORed combination of the following values:
   DISPLAY_CLEAR	-- clear the display
   DISPLAY_HOME	-- set the position to the beginning of display
  
  int display_putc(char c);
  
  This function should display it's parameter on the LED display in the
  current position. Returns the displayed character on success or -1 in
  case of failure.
  
  With this functions defined 'display' command will display it's
  arguments on the LED display (or clear the display if called without
  arguments).