drm/amd/pp: Refine get_gpu_power for VI

drm/amd/pp: Refine get_gpu_power for VI

pkgpwr is the average gpu power of 100ms. it is calculated by
firmware in real time.

1. we can send smu message PPSMC_MSG_GetCurrPkgPwr to read currentpkgpwr directly.

2. On Fiji/tonga/bonaire/hawwii, without PPSMC_MSG_GetCurrPkgPwr support.
   Send PPSMC_MSG_PmStatusLogStart/Sample to let smu write currentpkgpwr
   to ixSMU_PM_STATUS_94. driver can read pkgpwr from ixSMU_PM_STATUS_94.

Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>