drm/amd/display: fix some non-initialized register mask and setting

Fix some non-initialized register mask and update golden setting.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Duncan Ma <duncan.ma@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Charlene Liu <charlene.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>