drm/amd/display: Fix S3 topology change

Clean fake sink flag on resume if real sink connected.
Fixing S3 topology change problem like this:
1) x desktop with 1 or > displays
2) unplug display
3) suspend
4) replug same display
5) resume
without this change replugged display doesn't light up

Signed-off-by: Roman Li <Roman.Li@amd.com>
Reviewed-by: Sun peng Li <Sunpeng.Li@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>