drm/amd/display: register programming consolidation

remove redundant DPP_CLOCK_ENABLE in ipp. clock programmed by HWSS

Signed-off-by: Tony Cheng <tony.cheng@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>