cpufreq: vexpress-spc: remove lots of debug messages

This driver have been used and tested for year now and the extensive
debug/log messages in the driver are not really required anymore.
Get rid of those unnecessary log messages.

Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>