drm/amd/display: Add monitor patch for backlight off

drm/amd/display: Add monitor patch for backlight off

[Why]
Different panel need different time from backlight disable to end of valid video data,
if the time is too short, panel will flash when dpms off

[How]
Add monitor patch to control the time from backlight disable to end of valid video data,

Signed-off-by: Xiaodong Yan <Xiaodong.Yan@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>