drm/amd/display: Change EDID fallback condition

[Why]
Partially valid EDIDs on MST sinks are treated the same way as broken
EDIDs or read failures and result in a fallback EDID being used instead.

[How]
If edid_status is EDID_PARTIAL_VALID, prefer to use the valid EDID
blocks instead of using a fallback EDID.
Reviewed-by: Martin Leung <Martin.Leung@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Ilya Bakoulin <Ilya.Bakoulin@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/core/dc.c

@@ -4006,7 +4006,7 @@ struct dc_sink *dc_link_add_remote_sink(
 	 * Treat device as no EDID device if EDID
 	 * parsing fails
 	 */
-	if (edid_status != EDID_OK) {
+	if (edid_status != EDID_OK && edid_status != EDID_PARTIAL_VALID) {
 		dc_sink->dc_edid.length = 0;
 		dm_error("Bad EDID, status%d!\n", edid_status);
 	}