of: dynamic: Fix use after free in of_changeset_add_prop_helper()

If the of_changeset_add_property() function call fails, then this code
frees "new_pp" and then dereference it on the next line.  Return the
error code directly instead.

Fixes: c81f6ce ("of: dynamic: Fix memleak when of_pci_add_properties() failed")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/aKgljjhnpa4lVpdx@stanley.mountain
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

Author: Dan Carpenter

drivers/of/dynamic.c

@@ -935,13 +935,15 @@ static int of_changeset_add_prop_helper(struct of_changeset *ocs,
 		return -ENOMEM;
 
 	ret = of_changeset_add_property(ocs, np, new_pp);
-	if (ret)
+	if (ret) {
 		__of_prop_free(new_pp);
+		return ret;
+	}
 
 	new_pp->next = np->deadprops;
 	np->deadprops = new_pp;
 
-	return ret;
+	return 0;
 }
 
 /**