drm/amd/display: disable forced stutter disable after programming watermark

vbios will disable stutter pre-OS.  driver re-enable after programming watermark

Signed-off-by: Tony Cheng <tony.cheng@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>