ekf2: delete unused gps error norm field

src/modules/ekf2/EKF/ekf.h

@@ -648,7 +648,6 @@ class Ekf final : public EstimatorInterface
 	float _gps_velD_diff_filt{0.0f};	///< GPS filtered Down velocity (m/sec)
 	uint64_t _last_gps_fail_us{0};		///< last system time in usec that the GPS failed it's checks
 	uint64_t _last_gps_pass_us{0};		///< last system time in usec that the GPS passed it's checks
-	float _gps_error_norm{1.0f};		///< normalised gps error
 	uint32_t _min_gps_health_time_us{10000000}; ///< GPS is marked as healthy only after this amount of time
 	bool _gps_checks_passed{false};		///> true when all active GPS checks have passed
 

src/modules/ekf2/EKF/gps_checks.cpp

@@ -155,10 +155,6 @@ bool Ekf::runGnssChecks(const gnssSample &gps)
 	// Check the reported speed accuracy
 	_gps_check_fail_status.flags.sacc = (gps.sacc > _params.req_sacc);
 
-	// check if GPS quality is degraded
-	_gps_error_norm = fmaxf((gps.hacc / _params.req_hacc), (gps.vacc / _params.req_vacc));
-	_gps_error_norm = fmaxf(_gps_error_norm, (gps.sacc / _params.req_sacc));
-
 	// Calculate time lapsed since last update, limit to prevent numerical errors and calculate a lowpass filter coefficient
 	constexpr float filt_time_const = 10.0f;
 	const float dt = math::constrain(float(int64_t(gps.time_us) - int64_t(_gps_pos_prev.getProjectionReferenceTimestamp())) * 1e-6f, 0.001f, filt_time_const);