cve-check: create directory of CVE_CHECK_MANIFEST before copy

Create directory of the CVE_CHECK_MANIFEST variable before copy to it,
so that the variable can use an arbitrary directory name.

Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@weidmueller.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>