drm/amd/display: Limit display scaling to up to true 4k for DCN 3.1

commit c21b1053 upstream.

[why]
The requirement is that image width up to 4096 shall be supported

Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Agustin Gutierrez Sanchez <agustin.gutierrez@amd.com>
Signed-off-by: Nikola Cornij <nikola.cornij@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>