By Martin Domin Anthony Joshua has told Tyson Fury he is just a phone call away – while offering to fight him in his rival’s back garden. Joshua obliterated former UFC champion Francis Ngannou on Friday night, twice dropping his rival before knocking him out cold. The Brit is now in pole position to face the winner of Fury’s clash with Oleksandr Usyk back in Saudi Arabia on May 18. Joshua, 34, is set to be ringside for the fight which will crown the first undisputed heavyweight champion since Lennox Lewis in 1999. And he is ready to answer the call and finally realised his dream of holding all…