EKF: remove use of memset to initialise variable

When using a union of flags and integer value it is safer to initialise the value to 0 rather than memset the flags because the flags may not define all bits in the integer.

EKF/estimator_interface.cpp

@@ -435,7 +435,7 @@ bool EstimatorInterface::initialise_interface(uint64_t timestamp)
 	_time_last_range = 0;
 	_time_last_airspeed = 0;
 	_time_last_optflow = 0;
-	memset(&_fault_status.flags, 0, sizeof(_fault_status.flags));
+	_fault_status.value = 0;
 	_time_last_ext_vision = 0;
 	return true;
 }