drm/amd/pm: pp_dpm_sclk change for smu_v13_0_7

fetch the average gfxclk according to pmfw for smu_v13_0_7

Signed-off-by: Kenneth Feng <kenneth.feng@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>