state_machine_helper: rever explicitly handling unavaialble mission

It was already handled by the existing condition.

src/modules/commander/state_machine_helper.cpp

@@ -368,13 +368,9 @@ main_state_transition(const vehicle_status_s &status, const main_state_t new_mai
 
 	case commander_state_s::MAIN_STATE_AUTO_MISSION:
 
-		if (!status_flags.condition_auto_mission_available) {
-			ret = TRANSITION_DENIED;
-		}
-
 		/* need global position, home position, and a valid mission */
-		else if (status_flags.condition_global_position_valid &&
-			 status_flags.condition_auto_mission_available) {
+		if (status_flags.condition_global_position_valid &&
+		    status_flags.condition_auto_mission_available) {
 
 			ret = TRANSITION_CHANGED;
 		}