drm/amd/pm: Add support for DPM policies

drm/amd/pm: Add support for DPM policies

Add support to set/get information about different DPM policies. The
support is only available on SOCs which use swsmu architecture.

A DPM policy type may be defined with different levels. For example, a
policy may be defined to select Pstate preference and then later a
pstate preference may be chosen.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Asad Kamal <asad.kamal@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>