Restore Z_PROBE_PIN to pinsDebug_list.h

Marlin/src/pins/pinsDebug_list.h

 #if PIN_EXISTS(Z_MS2)
   REPORT_NAME_DIGITAL(__LINE__, Z_MS2_PIN)
 #endif
+#if PIN_EXISTS(Z_PROBE)
+  REPORT_NAME_DIGITAL(__LINE__, Z_PROBE_PIN)
+#endif
 #if PIN_EXISTS(Z_STEP)
   REPORT_NAME_DIGITAL(__LINE__, Z_STEP_PIN)
 #endif