drm/amd/display: Add blanked streams override to DML2.1

[WHY]
DML2.1 currently has no concept of a "blanked" stream. For cases like DPMS off,
things like UCLK p-state is always allowed, so PMO is not required to optimize
for it.

[HOW]
Add flag to DML2.1 display configuration to indicate all streams are blanked,
so certain operations and optimizations can be skipped for optimal programming
when displays are blanked.
Reviewed-by: Chaitanya Dhere <chaitanya.dhere@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Dillon Varone <dillon.varone@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_translation_helper.c

@@ -957,6 +957,7 @@ bool dml21_map_dc_state_into_dml_display_cfg(const struct dc *in_dc, struct dc_s
 	int stream_index, plane_index;
 	int disp_cfg_stream_location, disp_cfg_plane_location;
 	struct dml2_display_cfg *dml_dispcfg = &dml_ctx->v21.display_config;
+	unsigned int plane_count = 0;
 
 	memset(&dml_ctx->v21.dml_to_dc_pipe_mapping, 0, sizeof(struct dml2_dml_to_dc_pipe_mapping));
 
@@ -1010,8 +1011,14 @@ bool dml21_map_dc_state_into_dml_display_cfg(const struct dc *in_dc, struct dc_s
 					dml_dispcfg->plane_descriptors[disp_cfg_plane_location].overrides.uclk_pstate_change_strategy =
 							dml21_force_pstate_method_to_uclk_state_change_strategy(dml_ctx->config.pmo.force_pstate_method_values[stream_index]);
 				}
+
+				plane_count++;
+			}
 		}
 	}
+
+	if (plane_count == 0) {
+		dml_dispcfg->overrides.all_streams_blanked = true;
 	}
 
 	return true;