Meatpack::report_state on serial port init (#20903)

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

Marlin/src/sd/cardreader.cpp

@@ -1229,7 +1229,7 @@ void CardReader::fileHasFinished() {
   uint8_t CardReader::auto_report_sd_interval = 0;
   millis_t CardReader::next_sd_report_ms;
   #if HAS_MULTI_SERIAL
-    int8_t CardReader::auto_report_port;
+    serial_index_t CardReader::auto_report_port;
   #endif
 
   void CardReader::auto_report_sd_status() {

Marlin/src/sd/cardreader.h

@@ -267,7 +267,7 @@ private:
     static uint8_t auto_report_sd_interval;
     static millis_t next_sd_report_ms;
     #if HAS_MULTI_SERIAL
-      static int8_t auto_report_port;
+      static serial_index_t auto_report_port;
     #endif
   #endif