drm/amd/display: Add vendor specific LTTPR workarounds for DCN31

drm/amd/display: Add vendor specific LTTPR workarounds for DCN31

[Why]
Certain LTTPR require special workarounds in order to comply
with DP specifications.

[How]
Implement vendor specific sequences via DPCD writes to
vendor-specific LTTPR registers.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: George Shen <George.Shen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>