drivers/misc/lkdtm.c: cleanups

- make needlessly global functions static
- make lkdtm_module_{init,exit}() as __{init,exit}

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Cc: Ankita Garg <ankita@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>