mavlink_mission: don't reset vertex_count

Since vertex_count is in a union with do_jump_current_count, we can't
always reset the current count, otherwise the vertex_count ends up being
0.

src/modules/mavlink/mavlink_mission.cpp

@@ -1382,9 +1382,6 @@ MavlinkMissionManager::parse_mavlink_mission_item(const mavlink_mission_item_t *
 	mission_item->autocontinue = mavlink_mission_item->autocontinue;
 	// mission_item->index = mavlink_mission_item->seq;
 
-	/* reset DO_JUMP count */
-	mission_item->do_jump_current_count = 0;
-
 	mission_item->origin = ORIGIN_MAVLINK;
 
 	return MAV_MISSION_ACCEPTED;