Up/down buttons were reversed, swapped the assignments

Marlin/ultralcd_implementation_hitachi_HD44780.h

     #define BLEN_REPRAPWORLD_KEYPAD_F3 0
     #define BLEN_REPRAPWORLD_KEYPAD_F2 1
     #define BLEN_REPRAPWORLD_KEYPAD_F1 2
-    #define BLEN_REPRAPWORLD_KEYPAD_UP 3
+    #define BLEN_REPRAPWORLD_KEYPAD_UP 6
     #define BLEN_REPRAPWORLD_KEYPAD_RIGHT 4
     #define BLEN_REPRAPWORLD_KEYPAD_MIDDLE 5
-    #define BLEN_REPRAPWORLD_KEYPAD_DOWN 6
+    #define BLEN_REPRAPWORLD_KEYPAD_DOWN 3
     #define BLEN_REPRAPWORLD_KEYPAD_LEFT 7
     
     #define REPRAPWORLD_BTN_OFFSET 0 // bit offset into buttons for shift register values