gnss_position: removed covariance

msg/gnss_position.msg

@@ -4,7 +4,4 @@ bool fix_3d                 # Indicates if the fix is 3-dimensional (includes al
 
 float64 latitude            # Degrees latitude (positive = N, negative = S).
 float64 longitude           # Degrees longitude (positive = E, negative = W).
-float64 altitude            # Altitude above MSL [m]
-
-bool has_covariance         # Indicates if a covariance matrix is provided in this measurement.
-float64[9] covariance       # The covariance matrix of the measurement for lat,lon,alt.
+float64 altitude            # Altitude above MSL [m]