cpufreq: qcom-hw: Make use of cpufreq driver_data for passing pdev

Get rid of global_pdev pointer and make use of cpufreq driver_data for
passing the reference of pdev. This aligns with what other cpufreq drivers
are doing.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>