sh64: arch/sh64/kernel/signal.c: duplicate include removal

Remove the duplicate inclusion of linux/personality.h from
arch/sh64/kernel/signal.c

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>