drm/amd/display: Fix DCN42 null registers & register masks

drm/amd/display: Fix DCN42 null registers & register masks

[why]

The register lists used on DCN42 variants are different. Some reused
codepaths are trying to access registers not used.

[how]

Add DISPCLK_FREQ_CHANGECNTL, HUBPREQ_DEBUG, and HDMISTREAMCLK_CNTL to
the register lists.

Reviewed-by: Ovidiu (Ovi) Bunea <ovidiu.bunea@amd.com>
Signed-off-by: Matthew Stewart <Matthew.Stewart2@amd.com>
Signed-off-by: George Zhang <george.zhang@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>