drm/amd/pm: add callbacks to read/write sysfs file pp_power_profile_mode

Implement the sysfs API for getting/setting pp_power_profile_mode for
yellow carp.

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