lib/genalloc: fix device leak in of_gen_pool_get()

Make sure to drop the reference taken when looking up the genpool platform
device in of_gen_pool_get() before returning the pool.

Note that holding a reference to a device does typically not prevent its
devres managed resources from being released so there is no point in
keeping the reference.

Link: https://lkml.kernel.org/r/20250924080207.18006-1-johan@kernel.org
Fixes: 9375db0 ("genalloc: add devres support, allow to find a managed pool by device")
Signed-off-by: Johan Hovold <johan@kernel.org>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: <stable@vger.kernel.org>	[3.10+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: jhovold

lib/genalloc.c

@@ -899,8 +899,11 @@ struct gen_pool *of_gen_pool_get(struct device_node *np,
 		if (!name)
 			name = of_node_full_name(np_pool);
 	}
-	if (pdev)
+	if (pdev) {
 		pool = gen_pool_get(&pdev->dev, name);
+		put_device(&pdev->dev);
+	}
+
 	of_node_put(np_pool);
 
 	return pool;