drm/amd/display: Add NULL check for enabling dp ss

[Why]

The pointer for integrated_info can be NULL which causes the system to
do a null pointer deference and hang on boot.

[How]

Add a check to ensure that integrated_info is not null before enabling
DP ss.
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Sun peng Li <Sunpeng.Li@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1038,7 +1038,9 @@ static bool construct(
 	link->link_index = init_params->link_index;
 
 	link->link_id = bios->funcs->get_connector_id(bios, init_params->connector_index);
-	link->dp_ss_off = !!dc_ctx->dc_bios->integrated_info->dp_ss_control;;
+
+	if (dc_ctx->dc_bios->integrated_info)
+		link->dp_ss_off = !!dc_ctx->dc_bios->integrated_info->dp_ss_control;
 
 	if (link->link_id.type != OBJECT_TYPE_CONNECTOR) {
 		dm_error("%s: Invalid Connector ObjectID from Adapter Service for connector index:%d! type %d expected %d\n",