BTT SKR Pro runout pins (#18416)

Marlin/src/pins/stm32f4/pins_BTT_SKR_PRO_common.h

@@ -98,6 +98,19 @@
   #define Z_MIN_PROBE_PIN                   PA2
 #endif
 
+//
+// Filament Runout Sensor
+//
+#ifndef FIL_RUNOUT_PIN
+  #define FIL_RUNOUT_PIN                    PE15
+#endif
+#ifndef FIL_RUNOUT2_PIN
+  #define FIL_RUNOUT2_PIN                   PE10
+#endif
+#ifndef FIL_RUNOUT3_PIN
+  #define FIL_RUNOUT3_PIN                   PG5
+#endif
+
 //
 // Steppers
 //