Drop extra avr/pgmspace include in _Bootscreen.h

Addressing #9441

Marlin/src/config/examples/BQ/Hephestos_2/_Bootscreen.h

@@ -29,7 +29,6 @@
  * Use the Marlin Bitmap Converter to make your own:
  * http://marlinfw.org/tools/u8glib/converter.html
  */
-#include <avr/pgmspace.h>
 
 #define CUSTOM_BOOTSCREEN_BMPWIDTH  62
 

Marlin/src/config/examples/Cartesio/_Bootscreen.h

@@ -29,7 +29,6 @@
  * Use the Marlin Bitmap Converter to make your own:
  * http://marlinfw.org/tools/u8glib/converter.html
  */
-#include <avr/pgmspace.h>
 
 #define CUSTOM_BOOTSCREEN_BMPWIDTH  64
 

Marlin/src/config/examples/MakerParts/_Bootscreen.h

@@ -29,7 +29,6 @@
  * Use the Marlin Bitmap Converter to make your own:
  * http://marlinfw.org/tools/u8glib/converter.html
  */
-#include <avr/pgmspace.h>
 
 #define CUSTOM_BOOTSCREEN_BMPWIDTH  128
 

Marlin/src/config/examples/Malyan/M150/_Bootscreen.h

@@ -29,7 +29,6 @@
  * Use the Marlin Bitmap Converter to make your own:
  * http://marlinfw.org/tools/u8glib/converter.html
  */
-#include <avr/pgmspace.h>
 
 #define CUSTOM_BOOTSCREEN_TIMEOUT   1000
 #define CUSTOM_BOOTSCREEN_BMPWIDTH  128

Marlin/src/config/examples/gCreate/gMax1.5+/_Bootscreen.h

@@ -29,7 +29,6 @@
  * Use the Marlin Bitmap Converter to make your own:
  * http://marlinfw.org/tools/u8glib/converter.html
  */
-#include <avr/pgmspace.h>
 
 #define CUSTOM_BOOTSCREEN_BMPWIDTH  112
 

frameworks/CMSIS/LPC1768/lib/WString.h

@@ -26,7 +26,6 @@
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
-//#include <avr/pgmspace.h>
 
 // When compiling programs with this class, the following gcc parameters
 // dramatically increase performance and memory (RAM) efficiency, typically