uml: remove a duplicate include

Removed duplicated include file "kern_util.h" in
arch/um/drivers/ubd_kern.c.

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/drivers/ubd_kern.c

@@ -49,7 +49,6 @@
 #include "irq_user.h"
 #include "irq_kern.h"
 #include "ubd_user.h"
-#include "kern_util.h"
 #include "os.h"
 #include "mem.h"
 #include "mem_kern.h"