mfd: core: Increment of_node's refcount before linking it to the platform device

When an MFD device is added, a platform_device is allocated. If this
device is linked to a DT description, the corresponding OF node is linked
to the new platform device but the OF node's refcount isn't incremented.
As of_node_put() is called during the platform device release, it leads
to a refcount underflow.

Call of_node_get() to increment the OF node's refcount when the node is
linked to the newly created platform device.

Signed-off-by: Bastien Curutchet <bastien.curutchet@bootlin.com>
Link: https://lore.kernel.org/r/20250820-mfd-refcount-v1-1-6dcb5eb41756@bootlin.com
Signed-off-by: Lee Jones <lee@kernel.org>

Author: bastien-curutchet

drivers/mfd/mfd-core.c

@@ -131,6 +131,7 @@ static int mfd_match_of_node_to_dev(struct platform_device *pdev,
 	of_entry->np = np;
 	list_add_tail(&of_entry->list, &mfd_of_node_list);
 
+	of_node_get(np);
 	device_set_node(&pdev->dev, of_fwnode_handle(np));
 #endif
 	return 0;