drm/tegra: dsi: Add missing check for of_find_device_by_node

Add check for the return value of of_find_device_by_node() and return
the error if it fails in order to avoid NULL pointer dereference.

Fixes: e94236cd ("drm/tegra: dsi: Add ganged mode support")
Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231024080738.825553-1-nichen@iscas.ac.cn

drivers/gpu/drm/tegra/dsi.c

@@ -1544,9 +1544,11 @@ static int tegra_dsi_ganged_probe(struct tegra_dsi *dsi)
 	np = of_parse_phandle(dsi->dev->of_node, "nvidia,ganged-mode", 0);
 	if (np) {
 		struct platform_device *gangster = of_find_device_by_node(np);
+		of_node_put(np);
+		if (!gangster)
+			return -EPROBE_DEFER;
 
 		dsi->slave = platform_get_drvdata(gangster);
-		of_node_put(np);
 
 		if (!dsi->slave) {
 			put_device(&gangster->dev);