lkdtm: remove duplicated include of init.h

Fix following checkincludes.pl warning:
./drivers/misc/lkdtm/core.c
26	#include <linux/init.h>
    29	#include <linux/init.h>

Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Link: https://lore.kernel.org/r/20210628123512.38090-1-wanjiabing@vivo.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>