Revert "drm/amd/display: Refactor LTTPR cap retrieval"

This reverts commit 3b90318d.

[WHY]
Regressions unintentionally caused by change,
reverting until this can be resolved.

Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Michael Strauss <michael.strauss@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>