Merge pull request #1964 from AnHardt/Max6675again

Add variant for MAX6675 in M104

Marlin/Marlin_main.cpp

@@ -3134,7 +3134,7 @@ inline void gcode_M104() {
 inline void gcode_M105() {
   if (setTargetedHotend(105)) return;
 
-  #if HAS_TEMP_0 || HAS_TEMP_BED
+  #if HAS_TEMP_0 || HAS_TEMP_BED || defined(HEATER_0_USES_MAX6675)
     SERIAL_PROTOCOLPGM("ok");
     #if HAS_TEMP_0
       SERIAL_PROTOCOLPGM(" T:");