drm/amd/display: Add pp_smu functions for Renoir

This defines the interface for communicating requirements
between DC and powerplay.

Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>