cpufreq: qcom-hw: cleanup the driver for HW driver

Move the current code to support as per the upstream code and bring in
fixes required to support the EPSS driver. Fix em_register_perf_domain
as new API convention.

Change-Id: I267731a89a130d1fca5b1fb25aab95430a9099c7
Signed-off-by: Taniya Das <tdas@codeaurora.org>