drm/amd/display: Patch for extend time to panel poweron.

[WHY]
In eDP spec, the min duration in LCDVDD on-off-on sequence should be
500ms, some BOE panels need 700ms to pass.
[HOW]
Add patch to wait more time when eDP power on.

Signed-off-by: Hugo Hu <hugo.hu@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>