msm-cpufreq: Add snapshot of the MSM cpufreq doc from msm-3.10

Snapshot the documentation for msm cpufreq from msm-3.10 at commit
fb99d6226 ("qcom-cpufreq: Support parsing different freq tables
for each CPU clock").

Change-Id: I871766455ca9b8cf699b3578d86f86ad4b437297
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>