irqchip/alpine-msi: Fix refcount leak in alpine_msix_init_domains

of_irq_find_parent() returns a node pointer with refcount incremented,
We should use of_node_put() on it when not needed anymore.
Add missing of_node_put() to avoid refcount leak.

Fixes: e6b78f2c ("irqchip: Add the Alpine MSIX interrupt controller")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230102082811.3947760-1-linmq006@gmail.com