cve-check.bbclass: add layer to cve log

Lets include whcih layer a package belongs to and
add it to the cve logs

Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 00d965bb)
Signed-off-by: Steve Sakoman <steve@sakoman.com>