cpufreq layer doesn't call cpufreq driver's callback for any offline
CPU and so checking that isn't useful.

Lets get rid of it.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>