Update Marlin/ultralcd_implementation_hitachi_HD44780.h

Fix to a bug that I just introduced - sorry. Forgot about offset of string length.

Marlin/ultralcd_implementation_hitachi_HD44780.h

     char c;
     //Use all characters in narrow LCDs
   #if LCD_WIDTH < 20
-    	uint8_t n = LCD_WIDTH - 1 - 1;
+    	uint8_t n = LCD_WIDTH - 1 - 1 - strlen(data);
     #else
-    	uint8_t n = LCD_WIDTH - 1 - 2;
+    	uint8_t n = LCD_WIDTH - 1 - 2 - strlen(data);
   #endif
     lcd.setCursor(0, row);
     lcd.print(pre_char);
     char c;
     //Use all characters in narrow LCDs
   #if LCD_WIDTH < 20
-    	uint8_t n = LCD_WIDTH - 1 - 1;
+    	uint8_t n = LCD_WIDTH - 1 - 1 - strlen_P(data);
     #else
-    	uint8_t n = LCD_WIDTH - 1 - 2;
+    	uint8_t n = LCD_WIDTH - 1 - 2 - strlen_P(data);
   #endif
     lcd.setCursor(0, row);
     lcd.print(pre_char);