Fix garbled M119 output. Honor NUM_RUNOUT_SENSORS (#11948)

Marlin/src/module/endstops.cpp

     print_es_state(READ(Z_MIN_PROBE_PIN) != Z_MIN_PROBE_ENDSTOP_INVERTING, PSTR(MSG_Z_PROBE));
   #endif
   #if ENABLED(FILAMENT_RUNOUT_SENSOR)
-    #define FRS_COUNT (1 + PIN_EXISTS(FIL_RUNOUT2) + PIN_EXISTS(FIL_RUNOUT3) + PIN_EXISTS(FIL_RUNOUT4) + PIN_EXISTS(FIL_RUNOUT5) + PIN_EXISTS(FIL_RUNOUT6))
-    #if FRS_COUNT == 1
-      print_es_state(READ(FIL_RUNOUT_PIN) != FIL_RUNOUT_INVERTING, MSG_FILAMENT_RUNOUT_SENSOR);
+    #if NUM_RUNOUT_SENSORS == 1
+      print_es_state(READ(FIL_RUNOUT_PIN) != FIL_RUNOUT_INVERTING, PSTR(MSG_FILAMENT_RUNOUT_SENSOR));
     #else
-      for (uint8_t i = 1; i <=
-        #if   FRS_COUNT == 6
-          6
-        #elif FRS_COUNT == 5
-          5
-        #elif FRS_COUNT == 4
-          4
-        #elif FRS_COUNT == 3
-          3
-        #elif FRS_COUNT == 2
-          2
-        #endif
-        ; i++
-      ) {
+      for (uint8_t i = 1; i <= NUM_RUNOUT_SENSORS; i++) {
         pin_t pin;
         switch (i) {
           default: continue;
           case 1: pin = FIL_RUNOUT_PIN; break;
-          #if PIN_EXISTS(FIL_RUNOUT2)
-            case 2: pin = FIL_RUNOUT2_PIN; break;
-          #endif
-          #if PIN_EXISTS(FIL_RUNOUT3)
+          case 2: pin = FIL_RUNOUT2_PIN; break;
+          #if NUM_RUNOUT_SENSORS > 2
             case 3: pin = FIL_RUNOUT3_PIN; break;
-          #endif
-          #if PIN_EXISTS(FIL_RUNOUT4)
-            case 4: pin = FIL_RUNOUT4_PIN; break;
-          #endif
-          #if PIN_EXISTS(FIL_RUNOUT5)
-            case 5: pin = FIL_RUNOUT5_PIN; break;
-          #endif
-          #if PIN_EXISTS(FIL_RUNOUT6)
-            case 6: pin = FIL_RUNOUT6_PIN; break;
+            #if NUM_RUNOUT_SENSORS > 3
+              case 4: pin = FIL_RUNOUT4_PIN; break;
+              #if NUM_RUNOUT_SENSORS > 4
+                case 5: pin = FIL_RUNOUT5_PIN; break;
+                #if NUM_RUNOUT_SENSORS > 5
+                  case 6: pin = FIL_RUNOUT6_PIN; break;
+                #endif
+              #endif
+            #endif
           #endif
         }
         SERIAL_PROTOCOLPGM(MSG_FILAMENT_RUNOUT_SENSOR);