Use XYZ translated strings in dogm

Marlin/dogm_lcd_implementation.h

   u8g.setColorIndex(0); // white on black
   u8g.setPrintPos(2, XYZ_BASELINE);
   if (blink)
-    lcd_printPGM(PSTR("X"));
+    lcd_printPGM(PSTR(MSG_X));
   else {
     if (!axis_homed[X_AXIS])
       lcd_printPGM(PSTR("?"));
           lcd_printPGM(PSTR(" "));
         else
       #endif
-      lcd_printPGM(PSTR("X"));
+      lcd_printPGM(PSTR(MSG_X));
     }
   }
   u8g.drawPixel(8, XYZ_BASELINE - 5);
 
   u8g.setPrintPos(43, XYZ_BASELINE);
   if (blink)
-    lcd_printPGM(PSTR("Y"));
+    lcd_printPGM(PSTR(MSG_Y));
   else {
     if (!axis_homed[Y_AXIS])
       lcd_printPGM(PSTR("?"));
           lcd_printPGM(PSTR(" "));
         else
       #endif
-      lcd_printPGM(PSTR("Y"));
+      lcd_printPGM(PSTR(MSG_Y));
     }
   }
   u8g.drawPixel(49, XYZ_BASELINE - 5);
 
   u8g.setPrintPos(83, XYZ_BASELINE);
   if (blink)
-    lcd_printPGM(PSTR("Z"));
+    lcd_printPGM(PSTR(MSG_Z));
   else {
     if (!axis_homed[Z_AXIS])
       lcd_printPGM(PSTR("?"));
           lcd_printPGM(PSTR(" "));
         else
       #endif
-      lcd_printPGM(PSTR("Z"));
+      lcd_printPGM(PSTR(MSG_Z));
     }
   }
   u8g.drawPixel(89, XYZ_BASELINE - 5);