xen: remove duplicated #include

Remove duplicated #include('s) in
  arch/x86/xen/setup.c

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/setup.c

@@ -23,7 +23,6 @@
 #include <xen/interface/callback.h>
 #include <xen/interface/memory.h>
 #include <xen/interface/physdev.h>
-#include <xen/interface/memory.h>
 #include <xen/features.h>
 
 #include "xen-ops.h"