kmemcheck: remove duplicated #include

Remove duplicated #include in arch/x86/mm/kmemcheck/shadow.c.
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>

arch/x86/mm/kmemcheck/shadow.c

 #include <linux/kmemcheck.h>
 #include <linux/module.h>
 #include <linux/mm.h>
-#include <linux/module.h>
 
 #include <asm/page.h>
 #include <asm/pgtable.h>