Fix bug that breaks RS485 on the Opta

PB14 is used to enable USB on the PMC, but it is used for RS485 on the Opta.
Therefore, performing automatic detection on the Opta breaks RS485.

Author: Alrik Vidstrom

src/Arduino_POSIXStorage.cpp

@@ -224,7 +224,11 @@ enum BoardTypes detectBoardType()
 {
 #if defined(ARDUINO_PORTENTA_C33)
   return BOARD_PORTENTA_C33;
-#elif defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_OPTA)
+#elif defined(ARDUINO_OPTA)
+  // This case must be handled separately, because PB14 that enables USB on the PMC is used for RS485 on the Opta,
+  // so performing automatic detection on the Opta breaks RS485
+  return BOARD_PORTENTA_H7;
+#elif defined(ARDUINO_PORTENTA_H7_M7)
   #if (defined(AUTOMATIC_OVERRIDE_PORTENTA_H7) && defined(AUTOMATIC_OVERRIDE_PORTENTA_MACHINE_CONTROL))
     #error "You have defined AUTOMATIC_OVERRIDE_PORTENTA_H7 and AUTOMATIC_OVERRIDE_PORTENTA_MACHINE_CONTROL at the same time"
   #endif