AP_GPS: fragments_received is a bitmask not a count

libraries/AP_GPS/AP_GPS.cpp

@@ -1633,7 +1633,7 @@ void AP_GPS::handle_gps_rtcm_fragment(uint8_t flags, const uint8_t *data, uint8_
         // we have one or more partial fragments already received
         // which conflict with the new fragment, discard previous fragments
         rtcm_buffer->fragment_count = 0;
-        rtcm_stats.fragments_discarded += rtcm_buffer->fragments_received;
+        rtcm_stats.fragments_discarded += __builtin_popcount(rtcm_buffer->fragments_received);
         rtcm_buffer->fragments_received = 0;
     }
 
@@ -1662,7 +1662,7 @@ void AP_GPS::handle_gps_rtcm_fragment(uint8_t flags, const uint8_t *data, uint8_
     if (rtcm_buffer->fragment_count != 0 &&
         rtcm_buffer->fragments_received == (1U << rtcm_buffer->fragment_count) - 1) {
         // we have them all, inject
-        rtcm_stats.fragments_used += rtcm_buffer->fragments_received;
+        rtcm_stats.fragments_used += __builtin_popcount(rtcm_buffer->fragments_received);
         inject_data(rtcm_buffer->buffer, rtcm_buffer->total_length);
         rtcm_buffer->fragment_count = 0;
         rtcm_buffer->fragments_received = 0;