ipq806x: add & enable cpufreq support

This change set enables frequency scaling on ipq806x, which speeds-up
the CPU and allows it to achieve its max frequency.

These patches are cherry-picked & backported from the following location:
*130-132: linux-next
*133-143: LKML - https://lkml.org/lkml/2015/3/21/15
*144: derived from other qcom similar dts
*145: derived from https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.14/drivers/cpufreq/cpufreq-krait.c



Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45730 3c298f89-4303-0410-b956-a3cf2f4a3e73