Note that the POWER[89] processors are supported.

Documentation: cpufreq: Update supported powernv processors

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>