ts-i2c: removed pgm_read_byte define from gfx.c (unused) and updated README to mention we are using Adafruit gfx library code.

Author: brabo

examples/stm32/f4/stm32f429i-discovery/ts-i2c/README

@@ -5,5 +5,7 @@ This example sets up a very basic LCD display on the DISCO
 board and fills it with red.
 Pressing on the touchscreen will turn the screen green.
 
+It uses some graphics code that was inspired by AdaFruit graphics library.
+
 The stmpe811 example driver uses i2c to communicate with the
 touchscreen.

examples/stm32/f4/stm32f429i-discovery/ts-i2c/gfx.c

@@ -42,8 +42,6 @@
 #include <stdlib.h>
 #include "gfx.h"
 
-#define pgm_read_byte(addr) (*(const unsigned char *)(addr))
-
 struct gfx_state __gfx_state;
 
 void