drm/amdgpu: add powerplay support for CI asics

currently, for CI asics,
use dpm by default, amdgpu.dpm=-1.
when set amdgpu.dpm=1, enable powplay.
when set amdgpu.dpm=0, disable both dpm and powerplay.

when powerplay is stable on CI asics, ci_dpm will
be removed.

Reviewed-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>