By Jack Gallagher The FA have confirmed that Manchester United’s Harry Maguire, Manchester City’s Kyle Walker and Crystal Palace’s Sam Johnstone have all withdrawn from the England senior squad due to respective injuries. Walker was subbed off just 20 minutes intoEngland’s friendly defeat to Brazil at Wembley Stadium on Saturday evening, and after the game Gareth Southgate confirmed that the full-back was set to be assessed in the “coming days.” The England stalwart has now returned to Manchester City for said assessment. Fellow veteran defender Maguire was also taken off in the defeat, coming…