cpufreq: interactive: Remove sampling_down_factor

Remove sampling_down_factor feature.

This commit revert d094d236
(cpufreq: interactive: Add a sampling_down_factor for max frequencies)
and subsequent modifications related to sampling down factor.

Change-Id: Ib7ec0a918bd3e85a3425dbdeefcd2f2aecffe69c
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>