lkdtm: remove redundant initialization of ret

The variable ret is being initialized with the value -EINVAL however
this value is never read and ret is being re-assigned later on. Hence
the initialization is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>