cpufreq: rockchip: Provide runtime initialised driver

cpufreq: rockchip: Provide runtime initialised driver

This path introduces a rockchip-cpufreq driver, which can determine
available OPPs and select a suitable voltage for available OPPs
according to SoC version and leakage valuses in eFuse at runtime.

If all cpus of a cluster are downed, opp table will be removed,
prop-name and supported_hw are noneffective. So add a hotcpu notifier
to set them again when a cpu of the closed cluster is upped.

Change-Id: I43ab3e2cad4a9fefd5be5b0596cd841c392d7a8b
Signed-off-by: Finley Xiao <finley.xiao@rock-chips.com>