Remove GPS Baudrate locking for Seeed Xiao S3 Kit

The Seeed Xiao S3 Kit's default GPS is an L76K which operates at 9600 baud, so when this variant was defined that baud rate was specified.

However, this is a development board and it is expected that users can attach their own devices. This includes GPS, which may operate at a different baud rate. The current fixed baud rate prevents this, so this patch removes that setting.

This will revert to the regular automatic probe method. This will successfully detect the L76K as before (the same speed as before since 9600 baud is the first baud rate checked), but also allow other GPSes at other baud rates to be detected.

Thanks to @ScarpMarc for the report

Fixes https://github.com/meshtastic/firmware/issues/9373#issuecomment-3774802763

variants/esp32s3/seeed_xiao_s3/variant.h

@@ -50,7 +50,6 @@ L76K GPS Module Information : https://www.seeedstudio.com/L76K-GNSS-Module-for-S
 #define GPS_RX_PIN 44
 #define GPS_TX_PIN 43
 #define HAS_GPS 1
-#define GPS_BAUDRATE 9600
 #define GPS_THREAD_INTERVAL 50
 #define PIN_SERIAL1_RX PIN_GPS_TX
 #define PIN_SERIAL1_TX PIN_GPS_RX