cpufreq: governor: Rename 'cpu_dbs_common_info' to 'cpu_dbs_info'

Its not common info to all CPUs, but a structure representing common
type of cpu info to both governor types. Lets drop 'common_' from its
name.

Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>