drm/amd/display: Make create_stream_for_sink more consistent

We've got a helper function to call dc_create_stream_for_sink and one
other place that calls it directly. Make sure we call the helper
functions always since we need to update a bunch of things in stream and
don't want to miss that.
Signed-off-by: Harry Wentland <harry.wentland@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>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -2016,6 +2016,7 @@ static void update_stream_scaling_settings(const struct drm_display_mode *mode,
 	dst.width = stream->timing.h_addressable;
 	dst.height = stream->timing.v_addressable;
 
+	if (dm_state) {
 		rmx_type = dm_state->scaling;
 		if (rmx_type == RMX_ASPECT || rmx_type == RMX_OFF) {
 			if (src.width * dst.height <
@@ -2041,6 +2042,7 @@ static void update_stream_scaling_settings(const struct drm_display_mode *mode,
 			dst.width -= dm_state->underscan_hborder;
 			dst.height -= dm_state->underscan_vborder;
 		}
+	}
 
 	stream->src = src;
 	stream->dst = dst;
@@ -2367,11 +2369,6 @@ create_stream_for_sink(struct amdgpu_dm_connector *aconnector,
 		return stream;
 	}
 
-	if (dm_state == NULL) {
-		DRM_ERROR("dm_state is NULL!\n");
-		return stream;
-	}
-
 	drm_connector = &aconnector->base;
 
 	if (!aconnector->dc_sink) {
@@ -2418,7 +2415,7 @@ create_stream_for_sink(struct amdgpu_dm_connector *aconnector,
 	} else {
 		decide_crtc_timing_for_drm_display_mode(
 				&mode, preferred_mode,
-				dm_state->scaling != RMX_OFF);
+				dm_state ? (dm_state->scaling != RMX_OFF) : false);
 	}
 
 	fill_stream_properties_from_drm_display_mode(stream,
@@ -2800,7 +2797,7 @@ int amdgpu_dm_connector_mode_valid(struct drm_connector *connector,
 		goto fail;
 	}
 
-	stream = dc_create_stream_for_sink(dc_sink);
+	stream = create_stream_for_sink(aconnector, mode, NULL);
 	if (stream == NULL) {
 		DRM_ERROR("Failed to create stream for sink!\n");
 		goto fail;