Fix MKR Vidor 4000 Serial.dtr

[sameer]

This value is incorrect and prevents GPIO0 from being pulled at the right time, so esptool could not detect the board at all.
Now, it works perfectly with the added --no-stub parameter.
See this forum post for further discussion: https://forum.arduino.cc/index.php?topic=596970.0

[JAndrassy]

again, this is Vigor specific. it would not work with Uno WiFi, MKR1010 and Nano 33 IoT.
the solution must be ifdefed for Vigor

WiFiNINA/src/utility/spi_drv.cpp

Line 84 in 56c4cb9

#ifdef ARDUINO_SAMD_MKRVIDOR4000

[sameer]

again, this is Vigor specific. it would not work with Uno WiFi, MKR1010 and Nano 33 IoT.
the solution must be ifdefed for Vigor

WiFiNINA/src/utility/spi_drv.cpp

Line 84 in 56c4cb9

#ifdef ARDUINO_SAMD_MKRVIDOR4000

Unless there is something I am missing, the statement is already wrapped in an ifdef, so it is Vidor specific as is.

#ifdef ARDUINO_SAMD_MKRVIDOR4000
-    FPGA.digitalWrite(FPGA_NINA_GPIO0, (Serial.dtr() == 1) ? HIGH : LOW);
+    FPGA.digitalWrite(FPGA_NINA_GPIO0, (Serial.dtr() == 0) ? HIGH : LOW);
#else