AP_NavEKF2: don't reset EKx_GPS_TYPE when GPS has no vertical velocity

setting the parameter to 1 causes the following issues:

 - the GPS may not have vertical velocity at the time the parameter
   set happens, but may get it later when the GPS is fully configured

 - we may switch between GPS modules which do/don't have vertical
   velocity

 - the user may download parameters after the set(1), and end up with
   incorrect parameters they may later load onto the vehicle,
   permanently disabling use of vertical velocity

libraries/AP_NavEKF2/AP_NavEKF2_PosVelFusion.cpp

@@ -219,7 +219,8 @@ void NavEKF2_core::ResetHeight(void)
 
     // Reset the vertical velocity state using GPS vertical velocity if we are airborne
     // Check that GPS vertical velocity data is available and can be used
-    if (inFlight && !gpsNotAvailable && frontend->_fusionModeGPS == 0 && !frontend->inhibitGpsVertVelUse) {
+    if (inFlight && !gpsNotAvailable && frontend->_fusionModeGPS == 0 &&
+        dal.gps().have_vertical_velocity() && !frontend->inhibitGpsVertVelUse) {
         stateStruct.velocity.z =  gpsDataNew.vel.z;
     } else if (inFlight && useExtNavVel) {
         stateStruct.velocity.z = extNavVelNew.vel.z;
@@ -705,7 +706,8 @@ void NavEKF2_core::FuseVelPosNED()
             // test velocity measurements
             uint8_t imax = 2;
             // Don't fuse vertical velocity observations if inhibited by the user or if we are using synthetic data
-            if (!useExtNavVel && (frontend->_fusionModeGPS > 0 || PV_AidingMode != AID_ABSOLUTE || frontend->inhibitGpsVertVelUse)) {
+            if (!useExtNavVel && (frontend->_fusionModeGPS > 0 || PV_AidingMode != AID_ABSOLUTE ||
+                                  frontend->inhibitGpsVertVelUse || !dal.gps().have_vertical_velocity())) {
                 imax = 1;
             }
             float innovVelSumSq = 0; // sum of squares of velocity innovations

libraries/AP_NavEKF2/AP_NavEKF2_VehicleStatus.cpp

@@ -87,16 +87,6 @@ void NavEKF2_core::calcGpsGoodToAlign(void)
         gpsVertVelFilt = 0.1f * gpsDataNew.vel.z + 0.9f * gpsVertVelFilt;
         gpsVertVelFilt = constrain_float(gpsVertVelFilt,-10.0f,10.0f);
         gpsVertVelFail = (fabsf(gpsVertVelFilt) > 0.3f*checkScaler) && (frontend->_gpsCheck & MASK_GPS_VERT_SPD);
-    } else if ((frontend->_fusionModeGPS == 0) && !gps.have_vertical_velocity()) {
-        // If the EKF settings require vertical GPS velocity and the receiver is not outputting it, then fail
-        gpsVertVelFail = true;
-        // if we have a 3D fix with no vertical velocity and
-        // EK2_GPS_TYPE=0 then change it to 1. It means the GPS is not
-        // capable of giving a vertical velocity
-        if (gps.status() >= AP_DAL_GPS::GPS_OK_FIX_3D) {
-            frontend->_fusionModeGPS.set(1);
-            GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "EK2: Changed EK2_GPS_TYPE to 1");
-        }
     } else {
         gpsVertVelFail = false;
     }