drm/amd/powerplay: Get more than 8 level gfxclk states

To apply on Vega12 for more than 8 gfx dpm levels

Signed-off-by: Kenneth Feng <kenneth.feng@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>