drm/amd/display: move pplib/smu notification to dccg block

This is done to clear up the clock programming sequence
since the only time we need to notify pplib is after
clock update.

This also renames the clk block to dccg, at the moment
this block contains both clock management and dccg
functionality.

Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>