drm/amd/pm: make DAL communicate with SMU through unified interfaces

No need to have special handlings for swSMU supported ASICs.

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