drm/amd/display: PPLIB Hookup

[Why]
Make dml and integration with pplib clearer.

[How]
Change the way the dml formula is initialized to make its values more
clear. Restructure DC interface with pplib into rv_funcs.
Cap clocks received from pplib.

Signed-off-by: Jun Lei <Jun.Lei@amd.com>
Signed-off-by: Eryk Brol <eryk.brol@amd.com>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>