The AC97 clock detection is not accurate in some cases. This patch adds
an initial whitelist for audio devices gathered from RedHat's bugzilla:

https://bugzilla.redhat.com/show_bug.cgi?id=441087

As a side effect, white-listing might speedup kernel booting (AC97 clock
measuring code is not activated).
Signed-off-by: Jaroslav Kysela <perex@perex.cz>