cve-update-db-native: don't hardcode the database name

Don't hardcode the database filename, there's a variable for this in
cve-check.bbclass.

(From OE-Core rev: 0d188a9d)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>