[CPUFREQ] powernow-k8: Set transition latency to 1 if ACPI tables export 0

This doesn't fix anything, but it's expected that a transition latency of 0
could cause trouble in the future.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Cc: Langsdorf, Mark <mark.langsdorf@amd.com>
Signed-off-by: Dave Jones <davej@redhat.com>