cve-extra-exclusions: Clean up and ignore three CVEs (2xqemu and nasm)

cve-extra-exclusions: Clean up and ignore three CVEs (2xqemu and nasm)

Remove obsolete comments/data from the file. Add in three CVEs to ignore.
Two are qemu CVEs which upstream aren't particularly intersted in and aren't
serious issues. Also ignore the nasm CVE found from fuzzing as this isn't
a issue we'd expose from OE.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 68291026aab2fa6ee1260ca95198dd1d568521e5)
Signed-off-by: Steve Sakoman <steve@sakoman.com>