🎨 MKS Hardware Test followup (#22414)

Co-authored-by: Scott Lahteine <thinkyhead@users.noreply.github.com>

Marlin/src/pins/stm32f4/pins_MKS_ROBIN_NANO_V3.h

@@ -220,6 +220,12 @@
   #define WIFI_RESET_PIN                    PE9   // MKS ESP WIFI RESET PIN
 #endif
 
+// MKS TEST
+#if ENABLED(MKS_TEST)
+  #define MKS_TEST_POWER_LOSS_PIN           PA13   // PW_DET
+  #define MKS_TEST_PS_ON_PIN                PB2    // PW_OFF
+#endif
+
 //
 // Onboard SD card
 //