drm/amd/display: Ext displays with dock can't recognized after resume

[Why]
Needs to set the default value of the LTTPR timeout after resume.

[How]
Set the default (3.2ms) timeout at resuming if the sink supports
LTTPR

Reviewed-by: Jerry Zuo <Jerry.Zuo@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Ryan Lin <tsung-hua.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>