cve-check: add support for Ignored CVEs

cve-check: add support for Ignored CVEs

Ignored CVEs aren't patched, but do not apply in our configuration
for some reason. Up till now they were only partially supported
and reported as "Patched".

This patch adds separate reporting of Ignored CVEs. The variable
CVE_CHECK_REPORT_PATCHED now manages reporting of both patched
and ignored CVEs.

Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>