Respect GPS pins set in variant.h

src/esp32/architecture.h

@@ -77,12 +77,16 @@
 //
 
 #define GPS_SERIAL_NUM 1
+#ifndef GPS_RX_PIN
 #define GPS_RX_PIN 34
+#endif
+#ifndef GPS_TX_PIN
 #ifdef USE_JTAG
 #define GPS_TX_PIN -1
 #else
 #define GPS_TX_PIN 12
 #endif
+#endif
 
 // -----------------------------------------------------------------------------
 // LoRa SPI