drm/amd/display: Preserve refcount for S3 case.

Curent_context is zerroed out for suspend, keep the refcount.
Minor code move in dc_commit_context_no_check

Signed-off-by: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>