drm/bridge: lt9211: Convert to drm_of_get_data_lanes_count

Convert driver to use this new helper to standardize
OF "data-lanes" parsing.
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Maxime Ripard <maxime@cerno.tech>
Cc: Robert Foss <robert.foss@linaro.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
To: dri-devel@lists.freedesktop.org
Link: https://patchwork.freedesktop.org/patch/msgid/20220524010522.528569-5-marex@denx.de

drivers/gpu/drm/bridge/lontium-lt9211.c

@@ -686,7 +686,7 @@ static int lt9211_host_attach(struct lt9211 *ctx)
 	int ret;
 
 	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
-	dsi_lanes = of_property_count_u32_elems(endpoint, "data-lanes");
+	dsi_lanes = drm_of_get_data_lanes_count(endpoint, 1, 4);
 	host_node = of_graph_get_remote_port_parent(endpoint);
 	host = of_find_mipi_dsi_host_by_node(host_node);
 	of_node_put(host_node);
@@ -695,8 +695,8 @@ static int lt9211_host_attach(struct lt9211 *ctx)
 	if (!host)
 		return -EPROBE_DEFER;
 
-	if (dsi_lanes < 0 || dsi_lanes > 4)
-		return -EINVAL;
+	if (dsi_lanes < 0)
+		return dsi_lanes;
 
 	dsi = devm_mipi_dsi_device_register_full(dev, host, &info);
 	if (IS_ERR(dsi))