cpufeature: change logging for cpu features

During cpu on/off some of the cpu variant related messages are printed
flooding the kernel logs. Change the logging to pr_debug to avoid
excessive logging.

Change-Id: Ia80685da3bf2ec971c097848af5aa245f24d04dd
Signed-off-by: Channagoud Kadabi <ckadabi@codeaurora.org>