drm/amd/display: Pass tg and hubp inst instead of pipe index for SubVP

[Description]
- For pipe harvesting cases, the pipe index does not necessarily
  match up with the OTG instance, so pass index by OTG Instance instead
- For pipe split cases pass HUBP instance, since the split index is
  only used for HUBP programming
- Also check for OPP ID when accessing opp for pipe harvesting cases

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alvin Lee <Alvin.Lee2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>