bind: Exclude CVE-2019-6470 from cve-check

Issue only affects dhcpd with recent bind versions. We don't ship dhcpd anymore
so the issue doesn't affect us.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 30106ae6)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>