drm/amd/display: Move all DCCG RCG into HWSS root_clock_control

drm/amd/display: Move all DCCG RCG into HWSS root_clock_control

[why & how]
Enabling/disabling DCCG RCG should be done as a last-level step when
enabling/disable blocks. This is handled by HWSS root_clock_control
already during optimize_bandwidth.
However, dccg35_dpp_root_clock_control was missing the RCG enable
call on the disable path.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Ovidiu Bunea <ovidiu.bunea@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>