linux/generate-cve-exclusions: fix mishandling of boundary values

linux/generate-cve-exclusions: fix mishandling of boundary values

affected_versions in kernel_cves.json does not mean "first affected version
to last affected version" but actually "first affected version to fixed
version". Therefore, the variable names, conditional expressions, and
CVE_STATUS descriptions should be fixed.

For example, when the script was run against v6.1, if affected_versions was
"xxx to 6.1", the output was "cpe-stable-backport: Backported in 6.1", but
this should be "fixed-version: Fixed from version 6.1".

Signed-off-by: Yuta Hayama <hayama@lineo.co.jp>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
(cherry picked from commit 2064b2f9b92e2dff45dab633598b5ed37145d0b6)
Signed-off-by: Steve Sakoman <steve@sakoman.com>