cpufreq: dt: Convert few pr_debug/err() calls to dev_dbg/err()

We have the device structure available now, lets use it for better print
messages.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 896d6a4c0f41a93809b83f9e58aad73874a89d99)
Signed-off-by: Alex Shi <alex.shi@linaro.org>