drm/amd/display: Add missing dcn42 hubbub function pointers

drm/amd/display: Add missing dcn42 hubbub function pointers

This aligning commit combines:
- fix dcn42 det programming)
- fix missing dcn42 pointers
- fix SDPIF_Request_Rate_Limit programming value

V2: Add back dchvm_init for DCN42

Reviewed-by: Alex Hung <alex.hung@amd.com>
Reviewed-by: Leo Chen <leo.chen@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Signed-off-by: Chuanyu Tseng <Chuanyu.Tseng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>