In autoconf, don't probe Wire unless i2c device is set (#9081)

Found another bit of code that crashes my desktop, by probing the wrong i2c bus.

src/platform/portduino/PortduinoGlue.cpp

@@ -279,7 +279,7 @@ void portduinoSetup()
         //      RAK6421-13300-S1:aabbcc123456:5ba85807d92138b7519cfb60460573af:3061e8d8
         // <model string>:mac address :<16 random unique bytes in hexidecimal> : crc32
         // crc32 is calculated on the eeprom string up to but not including the final colon
-        if (strlen(autoconf_product) < 6) {
+        if (strlen(autoconf_product) < 6 && portduino_config.i2cdev != "") {
             try {
                 char *mac_start = nullptr;
                 char *devID_start = nullptr;
@@ -869,4 +869,4 @@ void readGPIOFromYaml(YAML::Node sourceNode, pinMapping &destPin, int pinDefault
         destPin.line = destPin.pin;
         destPin.gpiochip = portduino_config.lora_default_gpiochip;
     }
-}
+}