Merge pull request #2018 from fmalpartida/bugFixing

Bug corrected: persistent HOMING message when HOME button pressed for homing.

Marlin/Marlin_main.cpp

     if (!READ(HOME_PIN)) {
       if (!homeDebounceCount) {
         enqueuecommands_P(PSTR("G28"));
-        LCD_ALERTMESSAGEPGM(MSG_AUTO_HOME);
+        LCD_MESSAGEPGM(MSG_AUTO_HOME);
       }
       if (homeDebounceCount < HOME_DEBOUNCE_DELAY)
         homeDebounceCount++;