Follow-up the PR #5133 (M355 Case light)

・Add CASE_LIGHT_PIN into pinsDebug.h

Marlin/pinsDebug.h

   #if PIN_EXISTS(LED)
     PIN_SAY(LED_PIN);
   #endif
+  #if PIN_EXISTS(CASE_LIGHT)
+    PIN_SAY(CASE_LIGHT_PIN);
+  #endif
   #if PIN_EXISTS(MAIN_VOLTAGE_MEASURE)
     PIN_SAY(MAIN_VOLTAGE_MEASURE_PIN);
   #endif