This patch is to implement the processor fine grain feature for vangogh.
It's similar with gfx clock, the only difference is below:

echo "p core_id level value" > pp_od_clk_voltage

1. "p" - set the cclk (processor) frequency
2. "core_id" - 0/1/2/3, represents which cpu core you want to select
2. "level" - 0 or 1, "0" represents the min value,  "1" represents the
   max value
3. "value" - the target value of cclk frequency, it should be limited in
   the safe range

v2: fix some missing changes as Evan's suggestion.
v3: add version check and fix the restore.
Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>