EKF: Add a fixed wing mode with setter function

EKF/estimator_interface.h

@@ -181,6 +181,9 @@ public:
 	// set vehicle landed status data
 	void set_in_air_status(bool in_air) {_control_status.flags.in_air = in_air;}
 
+	// set vehicle is fixed wing status
+	void set_is_fixed_wing(bool is_fixed_wing) {_control_status.flags.fixed_wing = is_fixed_wing;}
+
 	// set flag if synthetic sideslip measurement should be fused
 	void set_fuse_beta_flag(bool fuse_beta) {_control_status.flags.fuse_beta = fuse_beta;}