drm/amd/display: configure lttpr mode

[Description]
1-Grant extended timeout request. Done once after detection
2-Configure lttpr mode based on lttpr support before LT
3-Account for lttpr cap when determining max link settings

Signed-off-by: abdoulaye berthe <abdoulaye.berthe@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>