🐛 Fix Z endstop enum

Followup to 92dea8e6cc

Marlin/src/module/endstops.h

   #if HAS_Y_MIN || HAS_Y_MAX
     , Y_ENDSTOP = TERN(Y_HOME_TO_MAX, Y_MAX, Y_MIN)
   #endif
-  #if HAS_Z_MIN || HAS_Z_MAX
+  #if HAS_Z_MIN || HAS_Z_MAX || HOMING_Z_WITH_PROBE
     , Z_ENDSTOP = TERN(Z_HOME_TO_MAX, Z_MAX, TERN(HOMING_Z_WITH_PROBE, Z_MIN_PROBE, Z_MIN))
   #endif
 };