drm/amd/display: Increase idle worker HPD detection time

[Why]
Idle worker thread waits HPD_DETECTION_TIME for HPD processing complete.
Some displays require longer time for that.

[How]
Increase HPD_DETECTION_TIME to 100ms.

Reviewed-by: Sun peng Li <sunpeng.li@amd.com>
Signed-off-by: Roman Li <Roman.Li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>