video: pxafb: Remove cpufreq policy notifier

The cpufreq policy notifier's CPUFREQ_ADJUST notification is going to
get removed soon.

The notifier callback pxafb_freq_policy() isn't doing anything apart
from printing a debug message on CPUFREQ_ADJUST notification. There is
no point in keeping an otherwise empty callback and registering the
notifier.

Remove it.

Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>