Use ENABLED with DISABLE_[INACTIVE_][XYZ]

Marlin/Marlin_main.cpp

 
   if (stepper_inactive_time && ms > previous_cmd_ms + stepper_inactive_time
       && !ignore_stepper_queue && !blocks_queued()) {
-    #if DISABLE_INACTIVE_X == true
+    #if ENABLED(DISABLE_INACTIVE_X)
       disable_x();
     #endif
-    #if DISABLE_INACTIVE_Y == true
+    #if ENABLED(DISABLE_INACTIVE_Y)
       disable_y();
     #endif
-    #if DISABLE_INACTIVE_Z == true
+    #if ENABLED(DISABLE_INACTIVE_Z)
       disable_z();
     #endif
-    #if DISABLE_INACTIVE_E == true
+    #if ENABLED(DISABLE_INACTIVE_E)
       disable_e0();
       disable_e1();
       disable_e2();

Marlin/planner.cpp

       block_index = next_block_index(block_index);
     }
   }
-  if (DISABLE_X && !axis_active[X_AXIS]) disable_x();
-  if (DISABLE_Y && !axis_active[Y_AXIS]) disable_y();
-  if (DISABLE_Z && !axis_active[Z_AXIS]) disable_z();
-  if (DISABLE_E && !axis_active[E_AXIS]) {
-    disable_e0();
-    disable_e1();
-    disable_e2();
-    disable_e3();
-  }
+  #if ENABLED(DISABLE_X)
+    if (!axis_active[X_AXIS]) disable_x();
+  #endif
+  #if ENABLED(DISABLE_Y)
+    if (!axis_active[Y_AXIS]) disable_y();
+  #endif
+  #if ENABLED(DISABLE_Z)
+    if (!axis_active[Z_AXIS]) disable_z();
+  #endif
+  #if ENABLED(DISABLE_E)
+    if (!axis_active[E_AXIS]) {
+      disable_e0();
+      disable_e1();
+      disable_e2();
+      disable_e3();
+    }
+  #endif
 
   #if HAS_FAN
     #ifdef FAN_KICKSTART_TIME