drm/amd/pm: add support to get dpm clock value for yellow carp

Implement the sysfs API for getting values of pp dpm
clocks(pp_dpm_socclk/mclk/fclk/vclk/dclk) for yellow carp.

Signed-off-by: Xiaomeng Hou <Xiaomeng.Hou@amd.com>
Reviewed-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>