cpufreq: cpu0: Update Module Author

Two people are maintaining it now, Viresh and Shawn. Add Viresh's details in
MODULE_AUTHOR() and copyright section.

Suggested-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>