Fix typo in GNSS_MODEL defination and usages for the UC6580 (#2988)

Correct the $CFGSYS init string for the UC6580 to init the receiver for:
GPS L1 & L5 + BDS B1I & B2a + GLONASS L1 + GALILEO E1 & E5a + SBAS

src/gps/GPS.h

@@ -23,7 +23,7 @@ struct uBloxGnssModelInfo {
 typedef enum {
     GNSS_MODEL_MTK,
     GNSS_MODEL_UBLOX,
-    GNSS_MODEL_UC6850,
+    GNSS_MODEL_UC6580,
     GNSS_MODEL_UNKNOWN,
 } GnssModel_t;