[CPUFREQ] conservative: remove 10x from def_sampling_rate

AMD users get particular hit by this issue (bug 8081) as it caps at
typically 90 seconds as the minimum period for a frequency change.
Harsh eh?  Years ago I borked this buy puting the 10x in the wrong
place...I fix that by removing it altogether.

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
Signed-off-by: Dave Jones <davej@redhat.com>