Fix: Debug Memory Dump size (#13957)

* Fix Memory Dump size

* Fix Compile error on Memory Dump

Marlin/src/gcode/gcode.cpp

   if (DEBUGGING(ECHO)) {
     SERIAL_ECHO_START();
     SERIAL_ECHOLN(current_command);
-    #if ENABLED(M100_FREE_MEMORY_WATCHER)
+    #if ENABLED(M100_FREE_MEMORY_DUMPER)
       SERIAL_ECHOPAIR("slot:", cmd_queue_index_r);
-      M100_dump_routine(PSTR("   Command Queue:"), (const char*)command_queue, (const char*)(command_queue + sizeof(command_queue)));
+      M100_dump_routine(PSTR("   Command Queue:"), (const char*)command_queue, (const char*)(command_queue) + sizeof(command_queue));
     #endif
   }