Increase Pico GPS FIFO Buffer size

As discovered and tested by @Mictronics, default Serial FIFO size
on the Pico is 32bytes, which is not enough for GPS messages.

This patch increases the Serial GPS FIFO buffer size to 256
for PICOs only.

fixes meshtastic#3989

src/gps/GPS.cpp

@@ -26,6 +26,8 @@
 
 #if defined(NRF52840_XXAA) || defined(NRF52833_XXAA) || defined(ARCH_ESP32) || defined(ARCH_PORTDUINO)
 HardwareSerial *GPS::_serial_gps = &Serial1;
+#elif defined(RPI_PICO_WAVESHARE)
+SerialUART *GPS::_serial_gps = &Serial1;
 #else
 HardwareSerial *GPS::_serial_gps = NULL;
 #endif
@@ -1201,6 +1203,10 @@ GnssModel_t GPS::probe(int serialSpeed)
 #if defined(ARCH_NRF52) || defined(ARCH_PORTDUINO) || defined(ARCH_RP2040) || defined(ARCH_STM32WL)
     _serial_gps->end();
     _serial_gps->begin(serialSpeed);
+#elif defined(RPI_PICO_WAVESHARE)
+    _serial_gps->end();
+    _serial_gps->setFIFOSize(256);
+    _serial_gps->begin(serialSpeed);
 #else
     if (_serial_gps->baudRate() != serialSpeed) {
         LOG_DEBUG("Setting Baud to %i\n", serialSpeed);
@@ -1268,6 +1274,10 @@ GnssModel_t GPS::probe(int serialSpeed)
 #if defined(ARCH_NRF52) || defined(ARCH_PORTDUINO) || defined(ARCH_RP2040) || defined(ARCH_STM32WL)
         _serial_gps->end();
         _serial_gps->begin(serialSpeed);
+#elif defined(RPI_PICO_WAVESHARE)
+        _serial_gps->end();
+        _serial_gps->setFIFOSize(256);
+        _serial_gps->begin(serialSpeed);
 #else
         _serial_gps->updateBaudRate(serialSpeed);
 #endif
@@ -1428,6 +1438,9 @@ GPS *GPS::createGps()
         LOG_DEBUG("Using GPIO%d for GPS RX\n", new_gps->rx_gpio);
         LOG_DEBUG("Using GPIO%d for GPS TX\n", new_gps->tx_gpio);
         _serial_gps->begin(GPS_BAUDRATE, SERIAL_8N1, new_gps->rx_gpio, new_gps->tx_gpio);
+#elif defined(RPI_PICO_WAVESHARE)
+        _serial_gps->setFIFOSize(256);
+        _serial_gps->begin(GPS_BAUDRATE);
 #else
         _serial_gps->begin(GPS_BAUDRATE);
 #endif