drm: sti: fix device leaks at component probe

commit 620a8f131154250f6a64a07d049a4f235d6451a5 upstream.

Make sure to drop the references taken to the vtg devices by
of_find_device_by_node() when looking up their driver data during
component probe.

Note that holding a reference to a platform device does not prevent its
driver data from going away so there is no point in keeping the
reference after the lookup helper returns.

Fixes: cc6b741 ("drm: sti: remove useless fields from vtg structure")
Cc: stable@vger.kernel.org	# 4.16
Cc: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20250922122012.27407-1-johan@kernel.org
Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ulrich Hecht <uli@kernel.org>

Author: jhovold

drivers/gpu/drm/sti/sti_vtg.c

@@ -141,12 +141,17 @@ struct sti_vtg {
 struct sti_vtg *of_vtg_find(struct device_node *np)
 {
 	struct platform_device *pdev;
+	struct sti_vtg *vtg;
 
 	pdev = of_find_device_by_node(np);
 	if (!pdev)
 		return NULL;
 
-	return (struct sti_vtg *)platform_get_drvdata(pdev);
+	vtg = platform_get_drvdata(pdev);
+
+	put_device(&pdev->dev);
+
+	return vtg;
 }
 
 static void vtg_reset(struct sti_vtg *vtg)