[WIP] LS20031 setup support

LS20031 is a MTK3339-based chip. Therefore, it should share some
heritage with other MTK3333 or MTK3339 chips. Re-use the L76B
commands for setup.

src/gps/GPS.cpp

@@ -1183,14 +1183,13 @@ GnssModel_t GPS::probe(int serialSpeed)
 
     PROBE_SIMPLE("L76K", "$PCAS06,0*1B", "$GPTXT,01,01,02,SW=", GNSS_MODEL_MTK, 500);
 
-    // Close all NMEA sentences, valid for L76B MTK platform (Waveshare Pico GPS)
+    // Close all NMEA sentences, valid for MTK3333 and MTK3339 platforms
     _serial_gps->write("$PMTK514,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*2E\r\n");
     delay(20);
 
     PROBE_SIMPLE("L76B", "$PMTK605*31", "Quectel-L76B", GNSS_MODEL_MTK_L76B, 500);
     PROBE_SIMPLE("PA1616S", "$PMTK605*31", "1616S", GNSS_MODEL_MTK_PA1616S, 500);
-
-    PROBE_SIMPLE("LS20031", "$PMTK605*31", "MC-1513", GNSS_MODEL_LS20031, 500);
+    PROBE_SIMPLE("LS20031", "$PMTK605*31", "MC-1513", GNSS_MODEL_MTK_L76B, 500);
 
     uint8_t cfg_rate[] = {0xB5, 0x62, 0x06, 0x08, 0x00, 0x00, 0x00, 0x00};
     UBXChecksum(cfg_rate, sizeof(cfg_rate));