rp2040: fix SerialNINAPassthrough functionality

The USB stack loses bytes here and there, need to double check it

fw update patch: replace single byte handling with

+uint8_t buf[16];
+uint8_t i = 0;

+    while (Serial.available() && i < sizeof(buf)) {
+      buf[i++] = Serial.read();
+    }
+    if (i > 0) {
+      SerialNina.write(buf, i);
+      i = 0;
+    }

+    while (SerialNina.available() && i < sizeof(buf)) {
+      buf[i++] = SerialNina.read();
+    }
+
+    if (i > 0) {
+      Serial.write(buf, i);
+      i = 0;
+    }

Author: facchinm

cores/arduino/USB/PluggableUSBSerial.h

@@ -277,10 +277,10 @@ class USBSerial: public USBCDC, public ::mbed::Stream, public HardwareSerial {
         return _bits;
     }
     bool dtr() {
-        return _dtr;
+        return (_dtr != 0);
     }
     bool rts() {
-        return _rts;
+        return (_rts != 0);
     }
 
 private:

variants/NANO_RP2040_CONNECT/pins_arduino.h

@@ -57,13 +57,15 @@ static const uint8_t SCK  = PIN_SPI_SCK;
 #define PIN_WIRE_SDA        (18u)
 #define PIN_WIRE_SCL        (19u)
 
-#define SERIAL_HOWMANY		2
+#define SERIAL_HOWMANY		3
 #define SERIAL1_TX			(digitalPinToPinName(PIN_SERIAL_TX))
 #define SERIAL1_RX			(digitalPinToPinName(PIN_SERIAL_RX))
 #define SERIAL2_TX			(digitalPinToPinName(25))
 #define SERIAL2_RX			(digitalPinToPinName(26))
 #define SERIAL2_CTS			(digitalPinToPinName(27))
 #define SERIAL2_RTS			(digitalPinToPinName(28))
+#define SERIAL3_TX			(digitalPinToPinName(25))
+#define SERIAL3_RX			(digitalPinToPinName(26))
 
 #define SERIAL_CDC			1
 #define HAS_UNIQUE_ISERIAL_DESCRIPTOR
@@ -84,11 +86,11 @@ void _ontouch1200bps_();
 #define SPI_SCK1		(digitalPinToPinName(29))
 
 #define NINA_RESETN		(24u)
-#define SerialNina		Serial2
+#define SerialNina		Serial3
 #define SerialHCI		Serial2
 
-#define NINA_GPIOIRQ	(24u) // LEDG pin (GPIO26 on NINA)
-#define NINA_GPIO0		(11u) // real GPIO0 on NINA
+#define NINA_GPIOIRQ	(21u) // LEDG pin (GPIO26 on NINA)
+#define NINA_GPIO0		(28u) // real GPIO0 on NINA
 
 #define SPIWIFI_SS		(26u)
 #define SPIWIFI_ACK		(27u)