drm/amd/display: Change viewport limit to 12 for DCN2

[WHY & HOW]
Viewport limit was set to 16 pixels due to an issue with MPO
on small viewports. This restriction does not apply and the
viewport limit can now be lowered.
Signed-off-by: Sung Lee <sung.lee@amd.com>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_resource.c

@@ -1064,8 +1064,8 @@ bool resource_build_scaling_params(struct pipe_ctx *pipe_ctx)
 
 	calculate_viewport(pipe_ctx);
 
-	if (pipe_ctx->plane_res.scl_data.viewport.height < 16 ||
-		pipe_ctx->plane_res.scl_data.viewport.width < 16) {
+	if (pipe_ctx->plane_res.scl_data.viewport.height < 12 ||
+		pipe_ctx->plane_res.scl_data.viewport.width < 12) {
 		if (store_h_border_left) {
 			restore_border_left_from_dst(pipe_ctx,
 				store_h_border_left);